British Journal of Obstetrics and Gynaecology August 1979. Vol. 86. pp 607-61 1
FETAL BREATHING MOVEMENTS AND FETAL DISTRESS BY
J. P. CALVERT*, Registrar AND
C. J. RICHARDS, Consultant Caerphilly District Miners’ Hospital, Caerphilly, Mid Glamorgan
Summary Twenty-seven pregnancies were monitored by antenatal cardiotocographs, daily fetal movement counts and an assessment of fetal breathing activity by real time scanning, and the results of these tests were related to the development of fetal distress during the first stage of labour. The proportion of time during which fetal breathing movements were present, determined over only a short period of time, was found to be a useful predictor of fetal behaviour during labour.
BREATHINGmovements occur in the human fetus from early pregnancy; and have been studied extensively by ultrasonic A scan (Boddy and Dawes, 1975). The recent development of real time scanning which displays a moving cqmposite picture is ideally suited to investigation of these movements (Fox and Hohler, 1977, Roberts et al, 1977) and is now the method most frequently used. Boddy and Dawes (1975) and Manning (1977), have suggested that the fetus which is destined to develop fetal distress during labour will show reduced fetal breathing movements (FBMs), but the picture is complicated by diurnal variation (Fox and Hohler, 1977, Roberts et a1 1977), maternal activity and blood glucose levels (Fox and Hohler, 1977), smoking (Manning and Feyerabend, 1976), uterine activity (Manning, 1977) and drug administration (Boddy and Dawes, 1975). Maternal assessment of fetal movements is often used as a simple outpatient indicator of fetal wellbeing, and both Pearson and Weaver (1976) and Sadovsky and Yaffe (1973) have suggested that a decline in the daily fetal movement
---* Present address: University Hospital
count (DFMC) to under 10/12 hours is a warning that the fetus might be in jeopardy. Assessment of fetal wellbeing can also be made by external cardiotocography and this can readily be applied to those patients who report a decrease in fetal movements. This study was undertaken to determine whether fetal breathing activity as assessed by real time scanning could be used as an index of fetal well-being, particularly behaviour during labour, and to augment assessment by daily fetal movement counts and external cardiotocography. PATIENTS AND METHODS The analysis is based on a total of 81 observation periods in 27 patients, giving an average of 3-0 scans per patient (range 1 to 8). Outpatients were studied once weekly, and inpatients two or three times each week. The majority of studies were performed in the early evening to reduce the effect of diurnal variation (Roberts et al, 1977). Indications for inclusion in the study were essential hypertension(3 patients), pre-eclampsia (9 patients), a clinical impression of intrauterine growth retardation (12 patients), weight loss (5 patients), reduced fetal movement (7 patients), antepartum haemorrhage (2 patients) or pro-
of Wales, Heath
Park, Cardiff.
607
608
CALVERT
longed pregnancy (2 patients). Some patients were included for more than one indication. Each patient kept a daily record of fetal movement using a Cardiff ‘Count to Ten Chart’, and had an antenatal cardiotocograph (CTG) and biparietal diameter (BPD) estimation performed on the same day as the FBM count. Cardiotocographs were scored by the ‘six point score’ (Pearson and Weaver, 1978). FBM assessment and CTGs were made with the patient in the supine position with a 15” lateral tilt to reduce caval compression. Scans were performed using an Ekolife real time scanner (Smith Kline) and a 3.5 MHz transducer. Abdominal palpation was performed first followed by a BPD measurement. To measure the FBM, either a longitudinal section of the fetal trunk or a transverse section showing the heart valve movement was obtained, and fetal breathing was considered to be occurring when there was rhythmical contraction and expansion of the chest wall. In the longitudinal section, this was accompanied by paradoxical movement of the abdominal wall. The total time during which these chest movements were seen was recorded with a stopwatch and expressed as a percentage of the total observation time (the FBM percentage). The stopwatch was stopped two seconds after the end of a breath if another breath had not started. Each observation period lasted for 15 minutes, except that if neither fetal body or limb movements nor fetal chest movements were seen in the first 15 minutes, observation was continued for a second 15 minute period because the uncompromised fetus is sometimes apnoeic for up to 30 minutes (Roberts et al, 1977). Time when the view was obscured by gross fetal movements was discounted. Fetal heart rates were monitored continuously during labour, and for the purposes of this study fetal distress was defined as the occurrence of late decelerations. The statistical analysis was by the Mann-Whitney test. RESULTS All 27 patients in the study were delivered between 37 and 42 weeks gestational age; 19 achieved spontaneous vaginal delivery, and 4were delivered by low forceps. Three of the forceps deliveries were for delay and one was for
a fetal bradycardia in the second stage attributed to a tight loop of cord around the baby’s neck. All these 23 babies had Apgar scores of 7 or over at one minute, and all except one were between the relevant 10th and 90th centiles for birth weight (Tanner and Thomson, 1970). The remaining four developed fetal distress during the first stage of labour. Three patients were delivered by emergency Caesarean Section of ‘light-for-dates’infants with respective Apgar scores at one minute of 4, 7 and 8. The fourth patient was delivered by mid-cavity forceps through an incompletely dilated cervix of a baby of appropriate weight and an Apgar score of 8 at one minute.
Patterns offetal breathing movements The most common pattern of FBM observed was of rapid (around 60/minute) small amplitude
. ...
60
.... ... rn
~~
~
No
distress
~~~~
Distress
FIG.1 The distribution of FBM percentage counts in the fetal ‘distress’ and ‘no fetal distress’ groups. Distribution of FBM percentages (time during which fetal breathing movements are present as a percentage of observation time) in the ‘fetal distress’ and ‘no fetal distress’ groups.
FETAL BREATHING AND DISTRESS
609
.
TABLEI Details of rhe 10 patients with abnormal results Patient No.
Smoker
1 2 3 4 5 6 7 8 9 10
Yes No Yes Yes Yes No No Yes Yes Yes
Last DFMC 8 9 5 0 0 >20
>20 >20 >20 8
Last CTG score*
Last FBM percentaget
5 5 5 5 4
57 50 48 60
No No No
0
4 4 4 5 5
1
Yes Yes Yes No Yes No
5 3 5 3
DFMC = daily fetal movement count CTG = cardiotocograph FBM = fetal breathing movement
percentage of total observation time.
Fetal breathing movements andjetal distress When the last recorded FBM percentage (2 to 5 days before delivery) is compared with the outcome, the group who developed no distress in the first stage had a mean FBM percentage of 34.7 (range 3 to 70). The patients who did develop fetal distress in the first stage had a mean FBM percentage of 2 . 7 5 (range 0 to 5). FBM percentages are shown in Figure 1 and the difference between the two groups is statistically significant (U = 4, p
FETAL BREATHING MOVEMENTS AND FETAL DISTRESS BY
J. P. CALVERT*, Registrar AND
C. J. RICHARDS, Consultant Caerphilly District Miners’ Hospital, Caerphilly, Mid Glamorgan
Summary Twenty-seven pregnancies were monitored by antenatal cardiotocographs, daily fetal movement counts and an assessment of fetal breathing activity by real time scanning, and the results of these tests were related to the development of fetal distress during the first stage of labour. The proportion of time during which fetal breathing movements were present, determined over only a short period of time, was found to be a useful predictor of fetal behaviour during labour.
BREATHINGmovements occur in the human fetus from early pregnancy; and have been studied extensively by ultrasonic A scan (Boddy and Dawes, 1975). The recent development of real time scanning which displays a moving cqmposite picture is ideally suited to investigation of these movements (Fox and Hohler, 1977, Roberts et al, 1977) and is now the method most frequently used. Boddy and Dawes (1975) and Manning (1977), have suggested that the fetus which is destined to develop fetal distress during labour will show reduced fetal breathing movements (FBMs), but the picture is complicated by diurnal variation (Fox and Hohler, 1977, Roberts et a1 1977), maternal activity and blood glucose levels (Fox and Hohler, 1977), smoking (Manning and Feyerabend, 1976), uterine activity (Manning, 1977) and drug administration (Boddy and Dawes, 1975). Maternal assessment of fetal movements is often used as a simple outpatient indicator of fetal wellbeing, and both Pearson and Weaver (1976) and Sadovsky and Yaffe (1973) have suggested that a decline in the daily fetal movement
---* Present address: University Hospital
count (DFMC) to under 10/12 hours is a warning that the fetus might be in jeopardy. Assessment of fetal wellbeing can also be made by external cardiotocography and this can readily be applied to those patients who report a decrease in fetal movements. This study was undertaken to determine whether fetal breathing activity as assessed by real time scanning could be used as an index of fetal well-being, particularly behaviour during labour, and to augment assessment by daily fetal movement counts and external cardiotocography. PATIENTS AND METHODS The analysis is based on a total of 81 observation periods in 27 patients, giving an average of 3-0 scans per patient (range 1 to 8). Outpatients were studied once weekly, and inpatients two or three times each week. The majority of studies were performed in the early evening to reduce the effect of diurnal variation (Roberts et al, 1977). Indications for inclusion in the study were essential hypertension(3 patients), pre-eclampsia (9 patients), a clinical impression of intrauterine growth retardation (12 patients), weight loss (5 patients), reduced fetal movement (7 patients), antepartum haemorrhage (2 patients) or pro-
of Wales, Heath
Park, Cardiff.
607
608
CALVERT
longed pregnancy (2 patients). Some patients were included for more than one indication. Each patient kept a daily record of fetal movement using a Cardiff ‘Count to Ten Chart’, and had an antenatal cardiotocograph (CTG) and biparietal diameter (BPD) estimation performed on the same day as the FBM count. Cardiotocographs were scored by the ‘six point score’ (Pearson and Weaver, 1978). FBM assessment and CTGs were made with the patient in the supine position with a 15” lateral tilt to reduce caval compression. Scans were performed using an Ekolife real time scanner (Smith Kline) and a 3.5 MHz transducer. Abdominal palpation was performed first followed by a BPD measurement. To measure the FBM, either a longitudinal section of the fetal trunk or a transverse section showing the heart valve movement was obtained, and fetal breathing was considered to be occurring when there was rhythmical contraction and expansion of the chest wall. In the longitudinal section, this was accompanied by paradoxical movement of the abdominal wall. The total time during which these chest movements were seen was recorded with a stopwatch and expressed as a percentage of the total observation time (the FBM percentage). The stopwatch was stopped two seconds after the end of a breath if another breath had not started. Each observation period lasted for 15 minutes, except that if neither fetal body or limb movements nor fetal chest movements were seen in the first 15 minutes, observation was continued for a second 15 minute period because the uncompromised fetus is sometimes apnoeic for up to 30 minutes (Roberts et al, 1977). Time when the view was obscured by gross fetal movements was discounted. Fetal heart rates were monitored continuously during labour, and for the purposes of this study fetal distress was defined as the occurrence of late decelerations. The statistical analysis was by the Mann-Whitney test. RESULTS All 27 patients in the study were delivered between 37 and 42 weeks gestational age; 19 achieved spontaneous vaginal delivery, and 4were delivered by low forceps. Three of the forceps deliveries were for delay and one was for
a fetal bradycardia in the second stage attributed to a tight loop of cord around the baby’s neck. All these 23 babies had Apgar scores of 7 or over at one minute, and all except one were between the relevant 10th and 90th centiles for birth weight (Tanner and Thomson, 1970). The remaining four developed fetal distress during the first stage of labour. Three patients were delivered by emergency Caesarean Section of ‘light-for-dates’infants with respective Apgar scores at one minute of 4, 7 and 8. The fourth patient was delivered by mid-cavity forceps through an incompletely dilated cervix of a baby of appropriate weight and an Apgar score of 8 at one minute.
Patterns offetal breathing movements The most common pattern of FBM observed was of rapid (around 60/minute) small amplitude
. ...
60
.... ... rn
~~
~
No
distress
~~~~
Distress
FIG.1 The distribution of FBM percentage counts in the fetal ‘distress’ and ‘no fetal distress’ groups. Distribution of FBM percentages (time during which fetal breathing movements are present as a percentage of observation time) in the ‘fetal distress’ and ‘no fetal distress’ groups.
FETAL BREATHING AND DISTRESS
609
.
TABLEI Details of rhe 10 patients with abnormal results Patient No.
Smoker
1 2 3 4 5 6 7 8 9 10
Yes No Yes Yes Yes No No Yes Yes Yes
Last DFMC 8 9 5 0 0 >20
>20 >20 >20 8
Last CTG score*
Last FBM percentaget
5 5 5 5 4
57 50 48 60
No No No
0
4 4 4 5 5
1
Yes Yes Yes No Yes No
5 3 5 3
DFMC = daily fetal movement count CTG = cardiotocograph FBM = fetal breathing movement
percentage of total observation time.
Fetal breathing movements andjetal distress When the last recorded FBM percentage (2 to 5 days before delivery) is compared with the outcome, the group who developed no distress in the first stage had a mean FBM percentage of 34.7 (range 3 to 70). The patients who did develop fetal distress in the first stage had a mean FBM percentage of 2 . 7 5 (range 0 to 5). FBM percentages are shown in Figure 1 and the difference between the two groups is statistically significant (U = 4, p
