British Journal of Obstetrics and Gynaecology September 1979. Vol. 86. pp 724-727
FETAL MOVEMENTS IN SMALL-FOR-DATES BABIES BY
G . J. JARVIS*,Registrar AND
H. N. MACDONALD, Consultant Obstetrician and Gynaecologist St James’s University Hospital, Leeds Summary Subjective assessment of daily fetal movement rates is a simple clinical guide to fetal well-being. Fetal death is unlikely to occur until the rate falls below 10 movements/l2 hours whilst a rate of less than 21 movements/l2 hours is strongly associated with a small-for-dates fetus and indicates the necessity for further assessment of placental function.
MODERNobstetric practice is concerned increasingly with early and accurate detection of the fetus at risk, especially if growth-retarded. Clinical assessment may only detect 30 per cent of these (Campbell and Kurjak, 1972) whilst ultrasound and biochemical measurements, although considerably more sensitive, are time consuming, costly and not always available. Subjective assessment of fetal movement is a simple, inexpensive and almost universally applicable procedure which may provide warning of fetal asphyxia or impending intrauterine death from chronic placental malnutrition (Pearson and Weaver, 1976; Sadovsky et al, 1973; Sadovsky and Yaffe, 1973). We present our experience of the technique analysed with particular regard to the incidence of small-fordates infants.
‘subjective consistency’ was stressed. The counting of movements commenced at 32 weeks gestation and ceased at delivery. Only the records obtained from patients who had counted movements on at least seven occasions were used. A total of 90 patients recorded 1222 DFMRs. Of these, 514 DFMRs were counted by 35 patients who constituted an obstetrically low-risk group (patients in whom there was no clinical reason to suspect poor placental function), whilst 708 DFMRs were counted by 55 patients who constituted an obstetrically high-risk group (patients in whom there was an indication to monitor placental function). A small-for-dates baby was defined as one whose birth weight fell on or below two standard deviations below the mean for the period of gestation, based on weights in the Aberdeen series (Thomson et al, 1968).
METHODS In-patients were asked to record the number of fetal movements felt over the same three onehour periods each day. This value, multiplied by four, gave the 12-hour daily fetal movement rate (DFMR). Each patient decided for herself what constituted a movement but the need for
RESULTS The ranges of DFMR recorded at each gestational week in both high and low risk groups are included in Table I with the respective arithmetic means and medians in addition to the 2.5th centile for the low risk group. Figure 1 portrays the means for each group with the 2.5th centile in the low risk patients. Although the overall range was wide, this was much less
* Present address : Senior Registrar, Jessop Hospital for Women, Sheffield.
TABLE I Daily fetal movement rate (DFMR) in low risk and high risk groups from 32 weeks gestation onwards Daily fetal movement rate (DFMR) High risk group
Low risk group Week of pregnancy Range 32 33 34 35 36 31 38 39 40
16-156 12-406 18-392 24-288 12-208 0-382 0-276 8-256 8-236
110 100 -
20 33 56 56 91 89 79 51 33
20-276 8-332 4-400 8-308 4-296 0-344 0-220 0-92 8-92
60 80 88 92 56 52 60 56 48
69 90 96 122 74 16 76 16 62
Number of records per plot
Low risk mean arithmetic
32 33 34 35 36 37 38 39 40 Weeks of Pregnancy FIG.1 Graphs of daily fetal movement rates (DFMR) against gestational age. Histograms of 2.5th centile (low risk group).
apparent in considering records for individual patients; this may have reflected individual variations in interpretation of bursts of fetal activity as ‘one’ or ‘several’ movements. The general tendency was for fetal activity to increase until the 35th week with a subsequent fall which was progressive only in the high risk group. Zero rates were recorded on 14 occasions by
Mean Median 66 92 85 95 76 15 60 55 43
60 60 64 56 84 60
40 32 32
Number of records per plot
2 ~ 5 t hcentile of low risk group
64 88 112 143 108 69 62 22
20 22 28 13 14 16 12 8
five patients, but only after the 36th week. Three of these quiet days had been preceded by a day of normal fetal activity and the other 11 occasions were coincidences of counting periods, reflecting fetal resting rather than inactivity, for movements were felt at other times during the day, recurred during the counting periods on the following day and ultimately all five women were delivered of live children showing no evidence of hypoxia or growth retardation. Twelve of the 90 babies were small-for-dates; there were three (8.6 per cent) in the low risk group and nine (16.4 per cent) in the high risk group. The only perinatal death, a stillbirth, occurred in a patient in the high risk group, a 31 year old gravida 7 whose six previous pregnancies had been uneventful. She had essential hypertension, a suspicious glucose tolerance test and suspected intrauterine fetal growth retardation. Urinary oestriol excretion, although rather low, had appeared to rise and serial assessments of biparietal growth had been satisfactory. The DFMR in the 38th week, when intrauterine fetal death occurred, had been variable and gave only brief warning of impending disaster. Table I1 shows the DFMR and urinary oestriol excretion in this patient. The fetal heart was absent within 12 hours of a DFMR of 8 being recorded. There was no evidence of either a cord complication or retroplacental bleeding at delivery but unfortunately the infant birth weight was not recorded. Following Pearson and Weaver (1976), we
JARVIS AND MACDONALD
TABLE I1 Urinary oestriol excretion and daily fetal movement rate (DFMR) during I1 days up to and including presumed day of intrauterine fetal death in one patient
Date in October
Oestriol excretion (pmo1/24 hours)
15 16 17 18 19 20 21 22 23 24 25
7.1 4.3 9.6 8.4 9.6 10 11.8 12.3 10.6 5.9
12 28 36
44 32 20 16 44 16 8
mg x 3.47
analysed our patients according to the occurrence of DFMRs of less than lO/day. Including zero recordings, 12 (13.3 per cent) of our 90 patients fall into this category, six of these within one week of delivery, but only two patients subsequently showed evidence of fetal compromise, the patient who had a stillbirth and one who had a small-for-dates infant, giving a false positive rate of 83 3 per cent and a false negative rate of 15.4 per cent. Although this TABLE I11 Daily fetalmovement rate (DFMR) in 12patients who had small-for-dates infants and one patient who had an intrauterine fetal death (ZUD) Patient No.
Birth Gestational age Lowest DFMR weight at delivery within 7 days of (9) (completed weeks) delivery
1 2 3 4 5 6 7 8 9 10 11 12 13
2511 1980 2550 2620 2080 2500 1077 2140 2560 2756 2630 2470 IUD
38 37 40 40 36 39 36 40 38 40 40 40 37
-* 57 24 20 20 20 20 16 12 12 12 8 8
* Excluded as no observations recorded during last two weeks of pregnancy.
group might have been smaller had we employed the method of continuous counting over a 12-hour period as used by Pearson and Weaver (1976), a cut-off point of 10 movements proved a poor predictor of small-for-dates infants and gave only brief warning of the impending intrauterine fetal death. The records of mothers delivered of a smallfor-dates or dead infant were analysed separately (Table 111). One set of recordings (patient No. I) was rejected as no observations had been made after the 36th week whilst delivery occurred two weeks later. Of the remaining 12 records, ten patients recorded DFMRs of less than 21 within 7 days of delivery (one on four occasions) giving a false positive rate of only 16.6 per cent. In our series of 90 patients, some 21 women recorded a DFMR of less than 21 (including zero recordings) on one or more occasions during the period of study. Ten women subsequently were delivered of a small-for-dates baby or a stillbirth giving a false positive rate of 52 per cent. Of the remaining 69 patients who always recorded a DFMR of greater than 21, only three subsequently were delivered of a small-fordates baby, a false negative rate of 4.3 per cent. Of 89 liveborn babies, six required intubation at delivery. Four of these might have been predicted as being ‘at risk’ because of a failure of their mothers to ‘count to 21’ on any day within a week of delivery. Three of these four babies were also small-for-dates.
DISCUSSJON Like Pearson and Weaver (1976) we have obtained satisfactory records from the vast majority of women asked to record DFMRs as in-patients or out-patients. However, we did not share their experiences of a steady fall in this rate from 32 weeks until term. We were impressed by the ‘patient acceptability’ of the method. It would seem feasable to record three one-hour sessions of movements rather than a 12-hour continuous record whilst advocating a ‘count to 21’ rather than a ‘count to 10’ early warning before commencing more expensive and sophisticated tests of placental function. The criticisms of this method were that recording times occasionally coincided with period of fetal resting and that as we multiplied by four it is theoretically possible (but most
unlikely) that we should be advocating a measurement of ‘5 -25’ movements by the Pearson and Weaver (1976) method, but they do not give sufficient detail of birth weights ’in their series for this to be tested. We lost only one baby in the patients recording movements. We think it very unlikely that a fetus will die of chronic placental insufficiency when the DFMR is greater than 10 and we can confirm the finding that ‘when fetal death occurred, fetal movements rapidly diminished 12 to 48 hours before death’ (Sadovsky et al, 1973; Pearson and Weaver, 1976). Although one may be able to allow some delay in planning delivery in the presence of a good DFMR, as over a weekend or a Bank Holiday, it was our experience that death may occur within 12 hours of the DMFR reaching single figures. As a failure to ‘count to 21’ seems to be associated with a small-for-dates baby or a stillbirth in 48 per cent of patients, we strongly advocate urgent and more sophisticated assessment of fetal well-being when this occurs. We conclude that the DFMR is a simple, inexpensive and
effective screening guide available to all Obstetricians and may indicate the pregnancy at risk of a late intrauterine or intrapartum death.
ACKNOWLEDGEMENTS We thank the nursing and medical staff (especially Dr K. Garrett) of the Obstetric Department of St Mary’s Hospital, Leeds, and our patients for their time, effort and cooperation in carrying out this study. REFERENCES Campbell, S., and Kurjak, A. (1972): British Medical Journal, 4,336. Pearson, J. F., and Weaver, J. B. (1976): British Medical Journal, 1,1305. Sadovsky, E., Polishok, W. Z . , and Malkin, A. (1973): Lancet, 1,1141. Sadovsky, E., and Yaffe, H. (1973): Obstetrics and Gynecology, 41,845. Thompson, A. M., Billewicz, W. Z . , and Hytten, F. E. (1968): Journal of Obstetrics and Gynaecology of the British Commonwealth,75,903.