Tf-fE NATIONAL BIRTH CENTER STUDY Par! !!!-!ntrapart!.!r!l

and !mmedla!P

PnGpatil_!m and Neon&4

Complications and Transfers, Postpartum and Neonatal Care, Outcomes, and Client Satisfaction

Judith P. Roo!zs, CNM, MS, MPH, Norman L. Vleatherby, Phq and Eunice K. M. Ernst, CNM, MPH

This is the final atide of the three-part report al the National Birth Center Study Eight

This

fs the final article from a threepart report oi the iiatio:wl Birth Center Study (NBCS). ‘Rx NBC3 was a prospective, descdpftve st;ldy of the experienceof ?7.856wo>nen whoreceived care at 84 bbth centers ++axqhout the United States behveen June l5,198S, and Cecembzr 31. 1987. Part I, published in the

July/August 1992 issue of the Joumol of NutseMfdwifey, described the

after labor and delivery until their dfs-

&dy

methodo&y,

charge from the centas

NBCS

subjectr with all women who

gave bii

compared

the

in the Onned State in 1966,

described the prenatal care and refermi practices of birih centers in the study, and described the women who were admitted to 6~ birth centers for intqmrtum care in reg& to characttfwght to be assc&ted ruitb perina+z! risk (1). Pan II, published in the September/October 1992 issue,

deafbed

the care prtided

to thase

ivomen and their newbarns during and (2). This tide, Part 111,descdbes complications experienced by the women during labot and by the women and newbcms scan after the births: trans.

thei; own birth center care Part III al,o describes associations medicallobstetrtc frequency andiw

of serious

trdl&lb

between

risk factors and the or soon after

labor and delivery. and uses that inlormation

were known

to NACC

during

were invited

to predict the effect vf con-

1985

to join

study: 89 centels paticipated.

iomplications

duling

Centers (NACC). All birth centers that and 1986

the

All but

to the

center. was used to C&CL data on dcm~r:phic and s:hcr :haractertstics that may be assoctated with pennatal

risk

and that

can be as-

centers were

sessed during an initial prenatal visit.

site-\njited to assess their compliance

Part II. completed when the woman

nine of the paixipattng with

correct data collectton

wcce-

was eith’rradmitted

to the binh center

sidering women with certan charac-

dures. Five centers were dmppeb from

in labor or dlscanttnued

terisfcs

the study because the site visits raised

care during the prenatal pedod. was

or prenatal complications

as

btfih center

concerns about the completeness and

used to collect information

about pre-

of the NBC.!?

validity of their data. Thus

the study

natal care, complications,

and Y+T-

was to describe the women who “se

is based on care provided

to clients

rals.

when

birth

mch~ble for birth center care The

main purpose

Pati

III,

completed

the

centers,

the care provided

to

of 84 birth centers; they induded more

woman

those u’orne”.

and the outcomes

of

than half of all birth centers known

the center after gtvtng birth

allows us

to determine whether birth center care

to be In weretin durhq 1985-1987. Certtftdd nurse-mid&es (CNMs)

parhlm

is safe.

were ma)or pdmary care providers in

fonnabon

about inhapartum

and im-

64 of the 84 binh centers in the NBCS.

med’ate postparh~mineonalal

cam and

that care. l’his information

Eleven

METHODS The

NBCS

scribed thoroughly

was

de-

in the fuxt article

of this series (1). A summary sented here along with s~ciftc

of the parricipatin~

birth cen-

ters were operated ~dm&ly methodology

to the analysis

is pre-

information and presen-

stetddans, three

by ob-

four by family physicians.

by lay or -licens&

midwives

(LM?), and two by physicians other than obstetricians or family physicians. Sixty-three

percent of the cen-

was either

kansfened

discharged

from

or was

to a hospital during inba-

care, was used to record in-

comdcations.

as rueI! as the &cum-

star~ces and results of transfers ta haspital care. Pzn

IV. completed dudnq

the four- to six-week pdstparmm low-up wit.

fair

was used to collect data

on care and complications neonatal and postpartum

during the period. the

tation of the data on complications,

ters in the study were licensed in their

health status if the moth&

bansfers. follow-up, and outcomes. The NBCS was conducted by the

states; 23% were accredited. Accred-

at the end of that oeriod.

itation was new and nFt widely avail-

“ations

able ai that time. Ten percent were

birth center care, A separate form was

Yational Association

of Chifdbearing

devoted exclun’vely orpdmaily to care of the poor, including several centers

-

that were serving

large numbers

indigent Iitspanicwomen.

of

Sixcenters

were owned by hospitals. Birth centers that were In operation during

1985-1987

but did not pai-

ticipate in the NBCS were likely to be b&ed in the %‘es:. !s Se run by LMs

.

by the mothers

and mfam and eval-

of their own

used to collect information

on a con-

venience sample of 20% of the tramfers (n = 387) regarding the time required to transport

women to hos-

pitals and how long they were m the hospitals before delivering their babies. The study began on June 15.1985. Each parttclpattng

center was given

orphysiciansotherthanobstehicians,

enough

10 enroll

its eunent

to save many iowlnwme

casetoad and new dlents

anticipated

dents, and

forms

to be unaccredded and not licensed

during the first 12 months oi data ml-

by state authantier.

ktioi. New centers joined

NBCS atiwly

Findings

horn the

are most representative of relwell-established birth centen

run by CNMe and obstehiciens.

Data

Collection

until November

1987.

the study

Some centers

that had completed their first set of forms mntinued to enroll their new dienb into the study until the enrollment -@od ended in late 1987. Other centers

completed

only

one set of

forms. A cohon of 17.856 u-omen ‘:zrn zx:z!!ed during a nearly twcand-one-half year period. The forms were completed by the women’s care protides. Collectton of data in each center was supewtsed

362

Journal of Nurs~.Midwifery

l

Vol. 37. No. 6. NovemberlDecPmber

1992

by a specially trained member of the

progress,

birth center staff.

fened for resptmtory dxtress but had

tal of only 11,814

normai birth weight and five-mi?nute

formation

Alar

3 special section of the report

were returned

Completed

monthly,

forms

read by op-

tical scanning, edited for inconsistent

and three had been time-

scores

of

7

or

higher.

Al-

or incomplete Items, and updated at-

though

ter obtaining

and thus could not review their ha-

additional

information

from the centers.

piid

we couid not identify ii is i.nlikdy

records. infants

for whom

Three

leaves

a safe out-

cane cannot be documented.

Follow-Up

ters in labor. including thme who had to hcspit&.

Eighty

seven percent of the women least one known

had at

follow-w

visit dur-

ing the four to six week;

after their

84.1%

and/or

had one or more

offtce

visits

with

a

member of the bkth center staff, and were examined

else. Two-thirds its,

campred who

by someone

of the women

who

had folkw-up

vts-

were transferred women

with were

89% not

of

the

transferred.

The birth centers trted tc obeln low-up infonnabon who

fol-

about the women

had been examined

by other

care providers and made special efforis to follow UD infants not noted as being in “g&d

condition”

when

discharged from the birth center (or hospital,

for

those

transfened).

who

had been

Follow-up

information

was obtained on all but 26 such infants We tried to determine whether any of those 26 infants had died but were unable to obtain

at least one

item of necessary information each Infant,

in most

about

instances

be-

cause the bit

center had closed, key

staff members

had moved,

and the

log book linking study numbem to the record of an individual client could not be accessed. However, staff from seven centers that had pm~ihd care

Data

Analysis

ing system.

and Presentation

Most of the data prexnted part of the report p&at”

m thawthird

to the 11,814

women who were admttted to the birth centers for intmTIarhml

care. or to a

subset of those &men.

Data from all

17.856

NBCS

in Table

subie&

are oresented

23 (see &ge

summadms

38?).

which

the use of birth center

care and outcomes for all women in the study. In addition, some analyses were based on subsets

of the date;

they are described in association with the-findings. Selected data on clients of the five centers that were dropped from the stud” because of ooor data walitv were examined to determine v&h& their

exclusion

had influenced

the

major findings. Subjectswith

mtssmg data were ex-

cluded from the denominators calculation

of most

during

of the percent-

ages. In order not to overstate provision number

of follow-up of women

the

care, the total

admitted

to the

birth centers and the total numbers of women

who were transferred

not transferred nominaton

or

were used as the de-

for percentages related to

this care.

and outcomes of la-

Data on twins Because there were 12 sets of twins, the actual number of infants

their centers had never experienced an intmpxtum stillbirth or maternal or neonatal death Of the 12 rematning unaccounted-for infants, five bad been born in hospitals after in-

tained infonnadon on all of the twins. dae an only one infant from each set of twins wasentered into the computerized record For example. if either twin had a complication, !he compBcation was recorded Thus most of the

hansfers

for

Journal of Nurse.Midwifew

failure

l

was

to

3 11.826.

Each woman

so&demographic haGxal!liie-stvle medtailobstetrtc scoring

system

received a

risk score. a berisk

yore.

r;sk xore.

and a The risk-

is described

in the

Methods section of the first paper (1,. A scoring

system

and summarize urgency

of

to cat:dgc:izc

the seriousness and

tntrapaltvm

mediate postpartum complications.

and im-

and neonatal

Information

was col-

lected to describe the incidence and severity of 23 spedt immediite

intmpartllm

postpartum

and

and neonatal

comp&catkms. Each complication was assigned a complication seriousness wxe between 1 and 3 to indicate its seliousness rqating

the risk of death

orperm.nentimpairmentandacomplkattcm urgency xore between 1 and 3 to reflect the need for rapid transfer to hospital care. A complication with a score of 3 on both scales, such as thick meconium or sustamed fetal dktress. is regarded in this analysis as a serious emergency. The NBCS plication

seriousness

and

com-

urgency

scaling system was based on authoritative literature study’s

advtsq,

and advice from the comrmttee and ex-

wrfenced clinicians. See Table 1 for e complete explanation of the scoring

to 14 of these subjecis certified that

fmpxtum

each

subied by three types of iisk relevant

organbed into a three-part disk-scor-

who were admitted to the birth cen-

2.4%

systems.

riod were used to charactetie

bor and delivery; this informatiun

been txmsfemd

home

risk-scoring

Da&a obtained during the prenatal pe-

to complications

We attempted to follow up all wmen

deliveries;

on a to-

infants. Detailedin-

on the twins is presented in

them

ihat any of

these eight infants died. That iour

tablesand percentagesreport

Althoush

we ob-

Vol. 37. No. 6. NouembPrlDecember 1992

system and the scores assigned to specific intrapmtum and immediate postpartum and neonatal compltcattons. The data on comp&cations refer on14. to comoli:ations that occuned while the and infants were in the bit centers. Although we collected information on cesarean secttons.

wok,en

363

scores. congenital anomalies. end neonatal deaths that were identifiedafterthe mothers orlnfankrae &w&erred to hospitals. we did “ot attempt to collect data on complications that occurred in hospitals. Apg3r

SUMMARY OF FINDINGS FROM PARTS I AND II The NBCS subjects included about the sane propotion of poor women as the total oooulatton of women who geve birth h i986, but they also included a relativelv high propotion of Hispanic women and much smaller proporttons of black women and of unmarded women. The birth center clientele were relatively low-risk with regerd to most of the behavioral/lifestyle factors associated with en increased incidence of poor pregnancy outcomes: however, they were less likely than other pregnant women to be@ prenatal care during the fiat trimester. Although most of the NBCS subjeck planned to use the birth centers for ell or most of their care, only huothirds of them were admitted to the birth centers for labor and deltwzy. Refenals related to prenatal complications were the most common reason for women to discontinue birth center care; however, more than half of the women who dropped out did so for other reasons, such as moving away or choosing to have a hospital birth. Prenatal care practices vati& by rbe professional preparetion of the persons providing the care. For instance, although obstetricians took care of B pardcularly low-risk group of women, thei patients were much more itkely to have uihasonograms dutiop prenatal cere. Fourteen percent of the women who obtetned prenata! ure through the W* centers were referred to a different sourceof intmpertum care. Almost 90% of the re’ermls occurred during the third trimester, more than a third during or after the 40th week of pregrarq, and 17% doting or

364

TABLE

t

The National Birth Center Study Complication Urgency Scoring System

Seriousness

and

During labor

Fetatheartrate indIaWe of distress TTanStent Suotetned Meconium

Light Tick Membranesmotored >I2 hours without l&or Hyperrensionwithout preeclampsia Preeclampsta Eclamp3ia Melprwntetio” Diagnosedbeforelabor Eieggnased duringlabor Diagnosedet birth Fw& tooo@% Second&ego Unrelievedpain: inadequatepain relief Metemel fever 4,ow One-minuteAwar 4,ooOg Pmtelm. < 2.501 g PC&e”“. 2.501-4.owl g Postterm.> 4,ooo g Unkmwn A” known

n

2E 3z 7.832 1.478 3 E 1l.E

deltway were due *a congenital anoraftes, comfwed tit” one of four deaths associatedwith tmansfersduring labor.

Vol. 37. No. 6. Nowm*bewDecembsr1992

%

AF

Ratet

1 (11

52.6

: 111) 8 (31 0

11.6 1.02

! (21 2

3.13 6.64

0.2 2.0 0.8 0.05 71.8 13.6 0.03 8.8 2.8 loo.0

15

1.27

The intrapart”“v”eo”atal mortality rate by @ty confmmzd to thr pat-km in most large data sek, with the htghest rata for ffmt babies and

379

for births to very high part&~women 17). The rates were 1.7 for nulliparous wonlen, 1.0 for women of pedty 1 or 2, 0.0 for women of parity 3 or 4, and 5.6 for women of patity 5 and higher lone death and only 177 births). Comparisons wfth Outcomes from Large Studies of Low-Risk Hospital&the

1.044 211 1.593 484 49” 383

0

_

80

1

12.50

959 277

;

- 1.04

260 138

1 ! 11) :

_

: 24

3 (1)

3.85 7.25

G.00

3

0

_ 1.ux.00

6: 12

0

_

i

-

0

4.00

250 96 15

: 0

TABLE 18 Outcomes: lntrapartum and Neonatal Deaths by Whether and WIten Transferred Women Whaher and WhenTmmfeened Not transferred Transferreddung labor Transfenedafterdelivery Au

n

%

9.945 1,466 403 11,814

84.2 12.4 3.4 1w.o

lntmpm+umand Neon&al koths -.A,,+ Rote1 4 (2) 4fl1 7 (41 15 171

0.40 2.73 17.37 1.27

‘Doalhrdueto reverecong~nita, anomali.rarebazzd m parenlherer. iPer l.snmwanenwhowereUaanJfened or ra asrpca.d.

380

Journal of NurrPMidtifay

.

This was a descdptive study, with no control group, and we know of no study inai &s&c; 3u!cmnes for a group of women who had hospital birthsend are tiy compareble to birth center clients. It is possible, however, to observe outcomee of “low-risk” or “uncomplicated” pregnandes by retrcepec&ely excluding individuals with certetn charactettstics (risk factors. complications,and/or outcomes) from date on a loge group of hospitalbiti. This has been done for various pw uow. We usedDubfishedreuoiis from &e such studids to provicle context for assessingthe outcomeS (mon&y rates, Apsar xores, and cesareen sectionmtes) for the women admitted to birth centers for fntmpxhrn care. Unforiunately. because these studies were designedfor other pmposes.their “low-dsk” or “uncom~&’ group are quite different from the birth center population. We tried ta create a more comparable group by eliminating women with certain demographic and life-stvle charactetistics.as well as wanen &II recognized mhdical and obstehic compL&ns, from a representative eemde of U.S. births. Unfortunately, we. eliminated ea many women that the remaining group is re’atiuely small. Deepite these liltations. the date from the six studies provide a frame of reference within which the birth center outcomes can be evaluated. Outcome date from thesesix grow of low-risk u,omen are presented with data fmm the NECS tn Table 19. E&b of the canpwtso” studies created e low-risk pregnancy data set by excludlng women with certain characted&s or oldcomes from a lager date

Vol. 37, No. 6, NovembenDecember 199.2

TABLE

19

Outcomes in Sk Studies of Low-Risk Hospital Births and in the Natiacai Birth Center S?udy

Beth IsraelHospital,Eaton. 196!-19758 Lowest-riskwomen, excludes infans with lethalcongenitalanomaiies Withmonltofingt Withoutmonitoring+ CommunityHospital.Cincinnati, !9?4-19759

.

With monitmingt 15 hmpitalsin Southeastern Minnpsota.1977-1979’0 Lowtisk women NationalNataMySuwey. 1980” Low&k births Unlverstwof UUnois and 11

12.055

76%

57% 4.144 2.293

base. Mothers of low birth weight infank and women with multiple gestattcr!s, no”“e*ex presonialions, repeat cesarean setions, or significant IlE&alorpreMtalcom~ti~werr

1.1 0.5

NA NA

10 Cl0

3.B 0.9

4.3 n.9

X? NA

N/4 NA

10.521

Jj%

kA

17

NA

NA

5.5

2.935

30% 19%

NA

2.5

NA

1.0

8.4

0.0 0.0

2.1 1.9

2.1 1.9

0.8

8.3

0.0 “.”

2.6 2.:

2.6 2.1

17

17 6

8,135

Gthout anomalies ParklandMemorialHospital.Dallas. 1982-1985’3 Uncomplicatedterm pregnancies 84 U.S. birthcenters, 1985-1987~ Infantsof women admittedfor i”tmpa*m care Au Withoutanomalk5 Tam births Au Wlthoutanomalies P&term births$ Au Withoutanomaltes

NP NA

14,618

42%

0.0

1.0

1.0

0.2

NA

11.826

66%#’

0415) 0.3 (4,

8: IT

1.3 (15, 0.7 IS)

0.6

4.4

9,871

0.2 (2) 0.2 (21

0.7 (71 0.3 (3)

0.9 (9) 0.5 (5)

0.6

41

1.305

2.3 (31 1.6 (2,

1.5 12) 0.8 (1)

3.8 (5) 2.3 (31

1.2

7.3

excluded from most if not all of the conlpartson studies. Neutm et al (8) stratified 15,846 ltve bts st B&t Israel Hospital in Boston inh five risk categories. In ad-

dam to the other exdustons. pregAndes resultingin intmpr&m deaths or congenfial anomalies incom@ibfe with life were omitted from the lowest risk group, which included 76% of

the women in the study. Amato (91 separated7,222 maternity pattents at a community hospital in Cincinnati into high-risk and low-risk qoups. In addition to the other exclusions. women with meconium-stainedamniotic fluid. @maturity, oxytocin stimulation. or prolonged rupture of the membrane; were &&d&l from t&low&k group. whichincludd only 57% of the women in the studu. Adamr (10) screened data on ,earIy 19,WfJ live births In 15 hospitals in southeastern Minnesota to Identify 10.521 low-dsk precmancies.He did not exclude m&h& of low birth weight infants or parous women with a fetus in the breechposttlon but made all of the other uslial exclus:onr and also excluded women who were younger than 19 or older than 34. Approximately55% of the women in the ortsinal data set remained after these exclusions. Data from the 1980 National Natality Survey (a probabiltty sample of 9,941 live births that occurred in the United States during 1980) was c&d to omit, m addition to other exclusions, uwnen who smoked more than 10 cigarettesper day, consumedmore than three alcoholicdrinks per week, had fewer than four prenatdl visits, or were unmarried, black, or younger than 18 years old. Only 30% of the original sample were included in the low-risk group, which was purpasef&y desigwd to apptimate the birth Center population (11; the special analysis of this date that is presented here was conduucwd by K. G. Keppel of the National Center for Health Statisticsj. Eden et al (12) screened 60.456 births at 12 hospka!sin a midwestern perinatal referral network to idenMv 11.592 “uncomdicated”term and p&a-m preg:.anciesin women between the ages of 16 and 39; their low-risk group included onlv 19% of the w&en the ofigir.al -data set Leueno et al (13) studied 15,586 pregnanciesthat resulted in 17,759 live births at Parkland Memorial Hospikl in Dallas. They excludedwomen with induced or complicatedlabors,

in

382

as quellas the other exclusions, and were left with 42% of the women in the low-risk group. Data on intrepartum and neonatal deaths, low five-minute Apgar scores. and cesareansecttons are presented for term births. postterm bhths, and 811births to women admitted to the NBCS birth centers for labor and delivery and for the low-risk women in eachof the comparisonstudies. some of which did not report each of these outcomes.The compartsonstud&s are presented in chronologic order; although they span 17 years, there is no apparent time-related trend. Most of the improvement in neonatal mortality d&g this period was due to improved wrvival of !ow birth weight infants (151. who were excludedfrom five of thr six compaison studies. With the be&t of retrospectionand the precisicn uf computers, lhese studis were better able than any group of cliniciansto detect and ellminate high-risk conditions such as Icw bin’, weight, buins, and nonved~r prej~intations Some of the cornpartson studies also excludedwomen with intmp~tum complications such as meco~~~m-stained anntonic tlukl and rwture of membranesfor 12 or more hours prior to onset of labor (Am&o [91j or all “complicated labors,” including those withmeconiumaid abnormal fetal heart rate (see reference 13). In addition, only two of the cornpmkm shldies kee references 10 and 11) used death certtftcates to astertain neonatal deaths. The other studies, basedon hospitalcl& oniy, would have missed any neonatal deaths that occurred after lnittal hospttal discharge.Although such deathsare rare, one of the 15 NBCS deaths was an apparent case of sudden infant death syndrome involving a baby who was heatthy at birth and in good condition when dischargedfrom the birlh center. The NWS deathrate would have been 1.2/1,ooObirths if thii death had not been counted. Neonatal mortality rates. Three of the compznisonstudies did not col-

Journal of Nurse-Mkhvifew

l

lect data on intrapartum deaths. The neonatal mortality rate (per 1.000 births) for the NBCS subjects (0.81 was lower than the rates for low-risk women in 15 hospitals in southeastern Minnesota (1.7) or in the 1980 National Natal@ Survey (2.51, and the neonatal mortally rate excluding deaths from lethal congenital anomalies was much lower for the NBCS subjects (0.31 than for low-risk women at the Beth Israel Hospital in Boston, In fa& the combinedinimparhen and nwno!nl de& mk?,fortheNBCS (1.3 for all women admitted to birth tenten for inkapatium care and 0.7 excluding lethal congenital anomalies) was lower than the neonatal death mtes from

these three studies.

Combined lntrapartum and neonatal mortality rates. AU three studies that presented date on intraparturn as well as neonatal deaths either excluded p&term pregnancies or presented that data separately. The combined intrapartum and neonatal niortajity late for term Pregnancieswa5 lower for the birth center dienk (0.9; than for au normal term Dresnandes In the study from a co&n&y hmoitai in Cincinnati (4.3) and was the as the rate ‘for’ normal term pregnancies wtth electronic fetal monitoring (0.9), even though wanen with meconlum-stalnedamniodcfiutd and prolonged ~lptore of rnembranes were excluded from the lowrisk community hospitd group. (Exelusion of women with those corn~iicaiions wouid hav= z!trntnated seven bf the 15 deaths from the NBCS data set.) The combined mortalttv rate for term deliveries was lower fo;the birth center cltents than for women delhat the University of Illtnots and 11 surrounding howit& (0.9 versus 2.1). However, the mortality rate for postterm birth was higher for the birth center clients than for the hospital births (3.8 versus 2.6 for all post&~ birthsand 23versus 1.9for~osttenn births excluding infants with &al congenital anomalies). me in~partum and neonatalmart&y rate for women

same

ertng

Vol. 37. No. 6, Nouemberficember 1992

with uncomulicated term meanancies delivered aiP&kmd Me’m&l Hos“ital in Dallas (1.01 was slishtl” hisher ihan the ratelo. birth c&t& clients who delivered at term (0.91, even though women wtth dystocta, abnormal fetal heart rate, or meconium in the amniotic fluid were excluded from the uncomplicated group in the Parkland study. Aftboush the combined inbaoarturn and>eonatal mortality rati for the birth center clients was not Mgher than rates from the studies of l&risk hospital births, the intrapartum mortality rate for the birth center clients was higher than the rates from most of the other studies that collected this data. There were no intrapartllm deaths among the women who had electronic fetal monitoling while in labor at the hospital in Cincinnati OT among the uncomplicated births at the 12 hospitals in Illinois or at Parkland H~~pttal in Dallas. However, these u& studies of highly selected uncomplicated pregnandes: all but 19% of the ofigtnal group of women were excluded from the sample studied at the University of Illinois. and women with meconium-stained amniotic fluid and many other kinds of intnparham complications were excluded from the samples from Ae hwitals in Cincinnati and Dallas. fn addition. the hiqher incidence of intmp&“m deaths at the birth centers was accompanied by a lower inctdence of neonaial deaths It is passible that the ability to perform a ceswea” section in resp0w.e to severe fetaldistress duringlaborina hospital resulh in live births of some modbund infants, thereby shifting some deaths from the intmparhtm to the neonatal period Apgar sccuos. The incidence of low lc 71 five-minute Awar scores was included in the rep02 of three of the comparkon SW&S. The inctdence among newboms of the btrth center cfients (0.6% for aU newborrz;, 0.6% for term births. and 1.2% for postterm births) was as low or leer

Journal d NurseMtkn,

.

than for infants of low-dsk women in the 1980 National Platality Survey 11.0%) or for uncompiiczted births at the University of Illinois and 11 surrounding hospitals (0.6% for term births and 1.7% for postterm birth+ but was hither than the rate for nncompltcated term pregnancies at Parkland Memorial Homital IO Z%l. Howeve-, this is to be e&&d, because women with abnormal fetal heart rates or meconium in the amniotic fluid were fxchded from the uncomplicated pregnancies in the Parkland study. Cesarean secttons. Three of the comparison shldies reported cesarcan &on rates Unlike mortality rates for low-risk births, the cesarean sec. ttor: rate did change ~ramaiicaljy durthe decade between 1977 (the first year of data collection for the earliest-of these three studies) and 1987 (the last year of data collection for the NBC?& from 13.7% in 1977 to 24.4% in 1987 (15, 16). The bilth centers’ rate of 4.4%. for births during 1985i9B7. is lower than the rates fo: any of the earlier studies The comparison study with the cesarean rate that is clasest to that of the bkth center cltentr was based on data collected during 1977-1979 in Minnesota. which is one of the ftve states with the lowest NTrent cesarean tion rates (17).

ing

Birth Center Clients’ Evaluations of Their Care The !ast page of the NBCS data collectton form wz used for an evaluatton by the clients of their own bii center care. The birth centers were kxtmcted to ask their clients to complete the form during their four- to six-week patparlum f&w-up v&it. Seventyhvo percent of the wmen completed the evaluations, the very positive results of which are shown in Tables 20 and 21. Although these data are useful, there are two important limitations!~ the vddtty nt these &dings: 1) Although thewomen’s names were not on the forms, their NBCS

Vol. 37, No. 6, NwemtoerlDecember

1992

subject identification numbers were, and the birth centers could not assure lhe women that their rinses v&d be anonymous. 2) Some of rhe women who were tmnsfened did not return to the birth centers for followup care. Thtt resulted in significant variation in the rate of completing the evaluDtion forms. Seventy& peercent of the women who were not tmnsferred comuleted evaluation farms. mmpared’with 54% of those who were involved in transfen. 67% of those who expzdenced serious emergency complications, and 47% of those who were delivered by cesawa” section Each woman who participated III the evaluatio~:s %zs a&; io assign the birth center a score between 1 and 5 cz ach of 35 specified item,. Nineteen of the items were related to how well the birth center had met the woman’s needs for information; six were related to the attitudes of the birth center staff and their sensitivity to the woman’s needs; 10 were related to the woman’s impressions of the birth center’s ptr& &i&s. For each item, tfx wcnnen were instructed !o gfw a score of 1 if the ‘element to be assessed was “not available.” a score of 2 to indicate the need for’impmvement, a score of 3 if the birth center’s performance was “adequate,” a score of 4 if the birth center’s periormance regarding the w&able was “goad,” and a score of 5 if it MS “excellent.” Cakulatton of mean ratings for each element excludedworesof 1. AsshwminTable 20, the mean score on every element was between 4.1 and 4.9. Only six of the mean scow were less than 4.Lthos-e regar&ng the adeq”acy of information on the avatlabtltty of s”ppatgrc”ps, theattimdesandsensttivity of physicians asswtiated with the birth center, and the food, libmy. telephone. and parking fadlitta The centers earned mean scores of 4.8 or higher for the adequacy of tir infomlation regarckng their sentces axI the quahffcatins of their staff, tne attx”des and sensitivfty of midwives.

303

TABLE 20 Client Evaluative Ratings of Birth Center Information Servlcoa. Stall and Facllttles: All Wemen Admttted to Birth Centers for Intrapatium Care

0.3 0.3 0.8 0.6 2.8 1.0 5.1 0.6 0.8 1.i 0.7

4.86 4.86 4.52 4.77 4.59 4.61 4.65 4.62 4.74 4.61 4.55

8,262

1.8

4.63

8,126 7,914

4.7 5.7 12.1 5.4

4.58 4.61 4.54 4.58

8,103

2.7 2.3 7.2

4.57 4.57 4.38

7,597 8,316 7,935 7,946 8.155 6.048

12.8 5.4 5.3 8.9 3.9 19.7

4.46 4.91 4.34 4.33

8,481 8,433 8,272 8,411 8.286 8,353 8,192 8,341 8.357 8.344 7,526

gz 8,153

Pbns for emergency ca;e Suppon groups available Staff attitudes and sensitivity Physicians Nurse-midtivesimidwives NUMS Birth assistants Receptionist others Impressions of the birth faakty Cleanliness Homelike environment Fcabsnack fadI&, Bath +nd bIi!ets As a place for children Lfbray for parenls Telephone setice Parkas space for family Emergency equipment

8,080

8,416 It% $353 8.082 8.003 8.209 8.285 6,211 7.960

0.3 0.3 7.1 0.3 2.5 9.i 1.4 1.6 0.7 1.9

4.74 4.68 4.83 4.85 4.43 4.74 4.58 4.36 4.48 4.10 4.53 4.61

to the predon. :,ti’ii categwy d iare provider at tte birth cater each wo”mn had used (Table 21). Of all the women who responded to this question, 94% indicated that they would choose a birth center if they had another baby. The percent who wouldchoose a blrthcenterwas highest among the clients of birth centers mn bu obstehicians and lowest amona women who used birth centers run by LMs. The difference. however. was due to the relatively large proportion of LM birth center clients who would choose a home birth If they had anotherbaby;only l.l%oftheLM birth center clients would prefer to have their next birth in a hospitt (including hospital bii moms). The percent who would use a birth center for their next pregnancy was iower among women who had been transferred (83% as compared to 94% for women who h.d not been transferred); however, even tine transferred women’s preference for birth centers WB “my high. &omen who had used birth centers run by physicians who were neither obsiebicians nor family physicians were most likely to want to go to a hospital for their next delivery. Most of the women would chwse to be attended during a subsequent birth by the kind of clinician who providedmostoftheircare.Thisvasmcst hue of women who had gone to bii centers run by CNMs. It was least true of those whd had gone to birth centers run by LMs, although the majority of the women who used LM birth centers would choose an LM to attend their next birth. About 65% to 66% of the women who had used birth centers run by obstetricians or fmnily physicians would return to the same kind of practitioner for a subspquent birth Most of the wanen who bad used birth centers run by any other type of physician wanted their next birth attendant to be a CNM. Ninety-six of the women who had used birth centen run by ohsteiricians and CNMs (jointly) would choose one of those categodes of at-

percent

384

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l

Vol. 37. No. 6. NowmberlDecember

1992

TABLE 21 C1fen.tEvaluations by ‘Type of Birth Cemer: All Women Admitted to Birth Centers for Intrapatium Care ___-._ .._._ f&i” Core Prmider at thy Rftih Center Attended by Each Wmm, (To,*

.

0.0 1.4 100.0

1.7 897 5.4 1.7 1.7 1OO.O

2.9 95.4 0.8 0.8 0.0 Km.0

14.0 84.9 1.1 0.0 00 lDo0

16.2

20.1

147 &17 0.0 44 1Do.o

55.6 15.5 7.1 I.7 Ea.0

55.8 402 1.3 13 1.3 100.0

18.3 23.9 1.4 535 2.8 loo.0

3.7 $x 0.0 loo.0 97.6

2.1 97.5 “4 1000 98.8

11 94.7 42 100.0 lW.O

45 92.4

1.9 963

18 0.9 0.4 1Gi.o

1.0 04 0.4 100.0

1.5

eo.4 0.4 7.2 0.5 100.0

664 27.3 3.8 1.4 1.1 1000

1.5 96.8 17

3.8 95.6 07

2.6 97.4 0.0

100.0

98.6

tendantsfortkirnextbirth; however, more would choca an OB than would chwxa a CNM. Almost all of the women would rec. ommend the birth center to a friend Lmore than 97% in each cateqonr). and almost all felt that the birth center’s charges bad bern reasonable (more than 95% in each category). Women whose birth centers were N” by obstebicianr.or by physicians other than obstetricians or family ptysicia”s were most likely to think that the charges were too high. Women whwe birth centerswere N” by LMs were most likely to tbfnk that the charges were too low. Fifty-four percent of the women involved in tmwfers completed the evakmtion forms; 97% said that they would rec. ommend the bkth center to a hiend

Journal d Nurse.Midw+fey

LMS fn _ 95)

OBE f” = 790)

other location All wrponses if you had anotherbaby, whom would you chwsz for your birth a”e”da”t? OU CNM Fp LM Other attendant An rerponses Do you feel tiai the bPlh center chargeswere: Tao high Reasonable TOOICW Au responses Said they would recommendtheir birth centerto a kiend

-

OBs and CNMS (n = 241,

Other

CNMS I” = 6,940,

FPS l” = 76, -_____

9:: 14

100.0

1W.O

99.1

ID00

and 83% would w the center during a subsequent pregnancy.

Use of Birth Center Care and Olltcomes, Summary

I

Table 22 summadzes the expefience of aff 17.856 wcnnen who were enrolled as subjects of the NBCS. Each of them had gone to a bii center for at least one complete prenatal visit Vey few were “risked out” duxing that uirjt Pamus wane” were more likely than “uffipamus women to be judged ineligible for birth center care. A slighdy higher pmpcxtiml of “tiparGus UUXE” left the centers after one visit for other reasow about 93% of both paity groupings retuned for continued pre”alaf care.

only

“a,. 37, No. 6. NwemberlDpcember 1992

.+&ions in = 2461

Ndipamus women were twiceas likely to be referred to other care duringfbeprenafalpenod; however. nullipaous and pamus women were equally likely to leave the birth centers for other reasons during prermtal care. But, because of the disparity in !xe”atal referrals. a lower!xrcentEKu bf nuffiparouswomen u&e admrtt;d to the centers for labor and deliway. Once adr&ted to the birth centersfor intmaparhuncare. nuffiparouswomen were more likely to be tinsfemzd an&or to experience a serkxs corn--Ò pfimfi”“. Two-thirds of the original 17,856 wane” wie admitted to the birth centers for intmpartum care. Fortyone percemtof the original cohort of nulffpxous women and 62% of the odginaf cohort of pamus women co”-

385

(NBCS) Began PIenat core iv BCs

0.5 0.9

_.____..._.

Discontinued for other reasons Nullipamuswomen Pamuswomen Admittedto BCs for IP care Nuikparouswomen Parouswomen

1,095 501 594 15.589 7,025 9,448 2,285 1.355 907 2,460 1,059 1,420 11,814 4,510 7.121

5.5 5.9 92.9 92.7 93.3 12.8 17.9 9.” 13.9 14.0 14.0 66.2 M).9 70.3

928 Ez

5.2 4.5 5.9

1.859 1,331 521 9,358 3.079 5.28Y

tinued in birth center care throughout their pregnancies and gave birth in the centers without being transferred or experiencing a serious problem. Outcomes for Women with Prenatal Medical/Obstetric Risk Factors This section describes the ultimate outcomes for women who had specifk medical or obstebtc conditions that were recognized and noted during prenatal care and for women with

385

6.1

16.589

100.0

100.0 100.0 13.8 19.3 9.5 15.0 15.1 15.0 71.2 65.5 75.4

11.814 4.510 7,121

100.0 100.0 100.0

928 z:

5.5 4.9 5.4

928 4.50

10.5 17.5 5.1

1,869 1,331 521

11.3 18.9 5.5

1.E 1,331 521

7.9 9.8 5.5 15.8 28.9 7.3

52.5 40.5 62.1

9,358 3,079 5,289

555 43.8 56.5

9.368 3,079 5,289

79.3 66.8 88.3

7.025 9,448 2,285 1.355 907 2,490 1.05Y 1,420 11,814 4,510 7,121

c&b&Mc risk as measured by the NBCS medicaUobs!etric risk scoring system (described in Table 2 of the first article of this series) Prelimlnaw analysis of this data showed signiicantly higher rates of prenatal referrak and intrapztum tramfers for the clients of birth centers Muned by hospitals as compared to the clients of all other birth centers (20.2% versw 12.7% prenatal referrals and 26.3% versus 16.4% inkapaium ban&n). The 2,421 clients of the six hospital-

Journal of Nurse-Midwifery .

owned centen were excluded from this analysis in order to avoid confounding related to this variable and to simplify interpretation of the data. The information needed for this analysls was collected d&g prenatalcare: therefore, it was also necessary to exelude wanen who made only one birth center visit Moie than 14,CQO womenof knownpaWvuhohadmore than one prena&l visit to one of the 75 hltih centers not owned by hwpit& were included in this analysis. The data are presented in Table

V01.37. No. 6. November/December 1992

TABLE 23 Continuation in Bltih Center (BCJ Care and Intrapartum (If’) Outcomes by Parity and the Presence of Specific Prenatal Conditiuns: Women Who Began Prenatal Care al 78 BCs Not Ourned by Hospitals

Journal of Nurse-Midwifery

E

19.8 9.8

163 13 6

63 9 766

181 344

23.2 6.2

14.4 49

69 : 90.6

44.2

320 239

30.6 23.4

5.9 10.0

63.5 666

203 158

369 10.8

148 10 1

57.6 83.6

366 552

iY3 42

i6.2 477

26 7.1

212 45.2

41 19

39 0 5.3

12.2 53

x3 7 AY 4

114 435

67 176

70. I 432

4.5 4.5

25.4 52.3

E

58.8 8.7

176 8.7

41.2 85.9

104 44.9

2:

28.6 400

28.6 200

42.9 4o.F

3 x

33.3 100.0

14.3 40.0

397 475

176 10.7

12.6 10 1

69.8 792

1:;

264 10.2

13.8 12.4

98 65

40.8 20.0

71 108

3i 41

93.5 85.4

6.5 7.3

0.0 73

E

65.0 :.4 7

6.8 89

28.1 564

229 224

69.0 4-60

8.7 14.3

22.3 39.7

238 130

46.7 32.3

5.3 3.1

124 81

66.5 395

2

46.8 35.4

l

69.5

66.7 _

_

277 375

23 8 9.3

12.6 93

69.7 35.9

486 680

59.8 774

52 106

11.5 4.7

5.7 2.8

846 74.4

X.6 730

520 692

51 45

392 2.2

9.8 6.7

58.8 91.1

30.6 631

0 3

3%3

_

667

49

329 11.9

68 9.0

621 808

17.5 45.6

50 89

20.0 13.5

14.0 12.4

70.6 787

15.7 31.3

490 64.6

102 83

49.0 27.7

8.8 4.8

45.1 69.0

22.1 44.6

3.2 3.7

403 568

5c 46

52.0 23.9

14.0 6.5

440 71.8

177 x.7

10.1 13.5

43.0 51.0

34 49

29.4 12.3

5.9 8.1

647 85.7

278 438 Iconanued)

Vol. 37. No. 6. NovemberiDecember

2;;

1992

387

TABLE 23

Co~ttinuation In Birth Center (BC) Care and lntrapadum (IP) Outcomes by Pari?y and the Presence of Specific Prenatal Conditions: Women Who Began Prenatal Care at 78 BCs Not Owned hy Hospitals IContInued)

388

308 278

58.1 338

3.2 4.7

38.6 615

98 130

42.9 354

19.4 15.4

37.8 492

241 300

17.8 10.0

14.5 17.0

67.6 73.0

1%

266 126

143 143

s9.1 73.1

7;

22.2 12.2

17.5 17.0

60.3 70.8

606 817

40.3 26.9

20.0 22.2

2.936 4.095

0.6 0.5

1,388 2,138

119 171

44.5 8.8

105

47.9 842

18.5 51.8

37.8 10.9

5.4 9.4

62.2 84.4

23.5 41.5

178 8.6

6.2 74

78.5 89.5

53.1 65.3

34.4 8.6

13.9 7.4

59.7 86.5

35.3 632

38 539

36.8 6.7

53 6.7

63.2 88.8

38.1 62.8

39.8 50.9

239 414

36.5 7.7

13.8 8.0

58.6 86.0

23.1 43.6

21.2 18.2

78.2 R1.3

2,297 3,330

233 4.7

8.1 5.8

72.7 VI.3

56.6 73 7

17.1 74

17.2 18.2

65.7 74.4

912 1,591

29.2 5.5

9.3 6.8

666 89.5

43.8 667

708 873

42.9 20.2

9.5 12.1

Cf.6 67.7

337 591

34.6 9.3

14.7 8.0

58.5 85.9

27.7 57.9

959 I.107

56.0 32.2

7.4 10.2

36.6 57.6

351 638

34.9 10.5

12.2 79

60.0 84.3

21.9 48.6

3,051 4.118

36.0 16.8

52.4 68.5

1.600 2.820

31.6 7.5

11.3 7.3

63.5 87.6

33.2 599

5.991 8,214 14.310

183 8.7 186

3,897 6,150

26.9

9.4 6.4 7.6

687 89.6

163 218

6.0

Journal of Nurse-Midwifery .

21.0

Vol. 37. No. 6, NwemberlDecember 1992

23. Each row wtthin this table presents information on women with a particular prenatal condition, =,howing the number of women who had the specified condition or risk score, the percentwho were referredto other care doling the prenatal period. the percent who left the birth center program for other wasor.;. and the percent who were admitted to the birtn centersforintrapartum care. The ne,: set of columns begins wirh the numher of women with the specified condition or risk score who were admitted to the birth centersfor tnbqxxtom care and shows what percent were transferred, what percent expwaxed a serious emergency cowli catto~. and what percent delivered in the Mrth centers without either being ban&red or having a serious comp&at& The !aS mlomn shows what percent of the women who began prenatal care at the birth centers and had the condition rematned in birth care and delivered their infants at the centers without havino a se& ous problem. For example, the first line of data in Table 23 describesthe outcomes for 283 nulliparour women who had some part of their prenatal care at the btt centers and were identtRed as having per&tent snemia: 56 of them flY.S%l were refened to other cad on the basis of risk, although not necessarilybecause of their anemia; 46 of them (16.3%) discontinued birth center care during the pwtatal p&d for home other reasonsLe.!& moving out of the area); 181 01 them (63.923 were admitted to the bkih centers for intrapartum care. Of the 181 women admitted to the centers for intfapartom care, 42 women or their infants (23.2%) were transferred to haspwAs, 26 (14.411 experienced sellous emergency compltcattonsduring their care at the centew and 125 (69.1%) gave btrth at the centers and did not experience seriousproblems. These percentages sUItomOrettXUl1OO%bGilIXsOme women were transferred end bad a sedcu emagency complkatins. The 125wornen whowerenotbansferred

center

Joumaf cdNurse-hlkiwtfety

l

and did not have a selious complithe nullfparous women continued in w.tfon included 44.2% oi the 283 birth center care and delivered their nulliparous women who began prebabies in the centea without either natal care at the birth centersand had transfersor sedou complications. persistent anemiaduring t&k prep rhiin percentofthQwol”e”war;I nanctes. referred to other care providers durAs shown in Table ‘22. nulliparity ing the prenatal period. Certain prewas assoctatedwith higher rates of natal conditions were assoctatedwith prenatal referrals. serious complicaveq high rates of prenatal referrals, tions, and intrapatim transfers to and a high percentageof women with hospital care. fSec?ue of this, data some mnditions discontinued birth f.x nulliparoue and parous women center care for other reaM”5. As a with each tuoe of orenatal medirea!t, fewer than half of the women c&obstetric ;i;k facto; are presented with any of the foIlwring ~renata; in seoarate lines in Table 23. The last compEc&ons were admiaed to the section of the table provides similar centers for in&w&urn care: wed&a for nulltparous and parous eclampttcs?mdrc& diabetes melliwomen by their medtcaVobstebicrisk tus. multi& geslado”s. pretoml lascoresand for all nullttarousand parbor, or va@nal bleeding atier the first 0”s won&?“. trimester. In addiSm, fewer than half Ttz dim&y between nulliwrow of the nulllparous women with ges and parous women is cor&ent tational diabetes, nonvertex pIesenthmuhout the data in Table 23. For tations, more than 12 hours of rupevery-condition except diabetes meltored membranes without labor, liiw. nulltparous women were more suspected inhautatne growth retarlikely than paroos women to be redam, of pastteml pregnancieswere ferred during preoatal care and were admitted to bit centers for intm less likely to be admitted to the birth parhun care. centers for intrapartum care; because Women with prenatal medionly 27 women had diabetes mellicaf/obskbtc lisk scores of zero had tus, those data are not stable. In adthe lowest rates of prenatal refer& dition, a high !ncidence of intraparinImparNm transfers. and sertous tom transfers among nulltparous emergency complications during or women with diabetes more rhan scan after bbor and delivery; thus they were most likely to be admitted compensated for th& lower rate ot prenatal r&r& in the end, only 14% to btrih centen for intmparium care of the nullfpxous diabeticwomen had and to have trouble-free deliveries in trouble-free birth in the centers. the centers. of the women who began w?natal care d tbe btt centers compared with 40% of the diabetic .nd had medt&obstebic risk scores women who were parous. Among;he ofzero,57%ofthen~w~n women with every kind of prenatal and 74% of the parous women decondition who were admitted to birth livered their babies in the centersand centen for twapartom care,thosewho had nosextousproblems. Forwomen were nolliparous were more likely to be tmnsfened. Although nulliparity in both patty groupings, the ftkeliwas associated witha high& iibad ofthis outcomebecomessmaller with each increase in their me& ddence of serious complications caUo&tetric risk scores Newtbeles~, among women with each type of prerncst of the women with mednatal condition, there was a higher caliobstemc ask scores of 1 or more rate of sedous complications among wer: admitted to the centers for hbar nulltparous women with every level and delivay, and high pro~~Mris of of overall medjcal/obstehic risk. those admitted to the centers delivwonlen with every prenatal eredin thecentenand hadnoserious condition and every level of mediCauobstebicrisk. a smaller percent of problems.

not

Among

Vol. 37. No. 6, NowmberKkczmber 1992

389

Could and Should Birth Centers Reduce the Incidence of Serious Complications By Changing Their Screening Craerta? The incidence of low Awar scores. intrapartom stillbirths, aAd neonatal deaths of infants born to women admitted to birth centers for labor and de::vey was vary low. Thus the following analysis is not directed et how to reduce deaths. It is directed at determining whether birth centers could adopt refed criteriathat would lower the rate of seriouscomplicationswithout 1eferdngkrge numbers of wornen who would not have had problems. It is based on the same date subset that was used for the analysis of outcome5 for women with s&k prenatal medtcaU&stehic risk factors. The concept of natemal risk screening began in the 19503, when epfdemiologic studies found asiociations between certain maternal characteristicsand a higher-than-average incidrxz ot poor pregnancy s’rrcomes 117-19) This led to inaeasir& fommfizedeffortsto Ident+ highrisk pregnant wxnen in order ~3 provide them with the most sophisticated and intensive obstebic and neonatal care. A complementary purpose of such tisk assessmentis identification of low-risk women in order to provide them with less expensive, 19% technolc@z care. sucl, as that in freestandingchildbirth centers. However, except for systemsthat categotie almost a!l women as high risk, no dsk assessment can predict all of the women who will develop complications during childbirth (20). Analyses of findings from studies of the use of specific maternal dsk assessmentinsbuments,mainly in the United States and Europe, have found their sensitivity to mnge from as low es 23% to as high as 94% i.e., 23% to 94% of the women who experienced poor pregnancy outcomes had been classified as high risk (17.20). However, the semitivky varied by the outcome being predicted: the Ill& sensitive tools used preterm deltvety and low

390

birth weight as risk factors for neonatal motility. Few of the tideiy used tools try to predict intrapatim complications. Unfortunately, sensitlulty (the ability oi the risk aesessmentto predict which women will have problems) is inversely related to spec@ity (the ability to predict which women will not have problems). As screeningbecomes more sensitive, it usually becomes lessspecific. When a relattvelv unspecific &ening process Is used, a large prop&ion of the women who will have normal deliveries are classified as high risk. Ascreenlngprocess that is sensitiveenough to ldentifv off of the women who will experience problems during labor and delivey would have to designate most (If not all) of the women as hlgh dsk. The reason for thb is illustratedby the date in Table 23: Althoush the inctdence of wious complfcationsincreaseswith increasing levels of medical&stetric risk, the incidenceamong women with no ciedrcdudbstemc risk iactors was not negligible. These Rndingsconcur with those from other large-scale studies that demo&rote that, althouJ, preaisting disease, previous obstetdc problems, and prenatal complications are highly correlated with the incidence of intmparhnn complicaUons, the absence of these factors does not guarantee a problem-free birth (21-24). One n identify a group of women who are low risk, but it is not possible to identify a group of wanen who have no risk at all. We wanted to determtne whether it would be possible to reduce the inddence of sertouscomplications in birth centers by refening all wornen with certain prenatal complications to other sourcesofin~opartumcare. We were looking for a way to make birth center referral practices more eensitive wid-nut m&rig them markedly lees specific. The referral practices of the centere in the NBCS resulted in excellent outcome+no maternal daeths. a low incidence of inhaparturn and neonatal mortality, a very

Joereal of Nurse~Midwtfery

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low rate of cesarean sections. and highly satisfied mothen. The be&is of providing this !w+cost, low-inter vention, family-centered car,! :o as many as possible oi thr winan who went it should not be traded lirlhtlv for redilctions in transfers and ok. ~lications. The data In T&la 23 swthat the transfer rate cou!d be reduced by two-thlrdsand the sedous complication rate could be reduced by one-fourth if birth centers accepted only porous women as clients and referred eve.y woman who hiipertenced any of the conditicns heluded in the NBCS medicai/ot&hic risk sale to a hospital for lntrz.partum care. However, such policies would reduce the number of women x. cepted for prenatal care by 42% and would reduce the numbe: admitted for labor and delivq by two-thirds. Because birth centers are achievir.3 good outcomes with their cuwent aiteriafor acceptingand refeting &en& such a radical reduction in the11abi!it;, *cl pi&:* care to woniiiii rvho SeeA their services would be counterproducfive. There is no reason to believe that such wlicies would result in better overeli outcomes for the group of women dented birth centercare Some individual women would have better outcomes, but others might expelewe iatmgenic problema related to unnecesaay cesareailsecttonsor other differences in their care Nevertheless, birth centers ore designed to provide care to women who we et low risk of obstetric complkations. Although the screening cfiteria should not be 50 sensitive that large numbers of women ore unnecessarily deterred irom using birth centers, It is In the best interest of birth centus themselves, as well ae their clientele, to enhance the screening process in order to reduce the incidence of serious complications in birth centers. Our approach to this challenge did not focus on reducing the rate of bansfers. Because it is impossible to identify a group of “no-tisk” women transferswill ahvaysbe llecexay, the; are an inherent and acceptable part

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Vol. 37, No. 6, NovembwDecember 1992

compttcations, reducingthe overatltate of sedous complicattons from 7.6% to 6.9% IP < .Ol). There would have ?eer?six fzuer ??nths (three of infants with zeveie conczxital anomalies). reducing the inir3partum and neo ratal matat+ rate per l.Mw) births from 1.4 L3 Z for infants withour severe anomalies)to 0.9 IO.6 for infants