Planned caesarean section decreases the risk of adverse perinatal outcome due to both labour and delivery complications in the Term Breech Trial

Authors


Dr M. Hannah, Maternal Infant and Reproductive Health Research Unit, Centre for Research in Women's Health, University of Toronto, Suite 751, 790 Bay Street, Toronto, Ontario, Canada M5G 1N8.

Abstract

Objective  To determine if the decreased risk of adverse perinatal outcome, with a policy of planned caesarean, in the Term Breech Trial, was due to a reduction of problems of labour, problems of delivery or unrelated problems.

Design  Secondary analysis of data from the Term Breech Trial, a randomised controlled trial of planned caesarean versus planned vaginal birth for the singleton fetus in frank or complete breech presentation at term.

Setting  Women were recruited from 121 centres in 26 countries.

Population  Women who were enrolled in the Term Breech Trial.

Methods  Adverse perinatal outcome was classified as due to labour, due to delivery, due to neither labour nor delivery or unexplained by an experienced obstetrician who was masked to allocation group. The risk of an adverse outcome in each category was compared according to intention to treat and also by actual method of delivery.

Main outcome measures  Adverse perinatal outcome (excluding lethal congenital anomalies) that was due to labour, due to delivery, due to neither labour nor delivery or unexplained.

Results  Planned caesarean was associated with a lower risk of adverse outcome due to both labour (RR 0.14, 95% CI 0.04–0.45, P < 0.001) and delivery (RR 0.37, 95% CI 0.16–0.87, P= 0.03), compared with planned vaginal birth. Prelabour caesarean and caesarean during early labour were associated with the lowest risk and vaginal birth was associated with the highest risk of adverse outcome due to both labour (0%, 0.4% and 2.2%, respectively) and delivery (0.2%, 0% and 3.1%, respectively).

Conclusions  Planned caesarean decreases the risk of adverse perinatal outcome due to both problems of labour and problems of delivery for the singleton fetus in breech presentation at term, compared with planned vaginal birth.

INTRODUCTION

Breech presentation occurs in 3% to 4% of pregnancies at term.1 There is now strong evidence that a policy of planned caesarean reduces the risk of adverse perinatal outcome, compared with a policy of planned vaginal birth.2,3 Much of this evidence comes from the Term Breech Trial, an international multicentre randomised controlled trial which enrolled 2088 women from 121 centres in 26 countries.2 The Term Breech Trial compared planned caesarean with planned vaginal birth for women with a singleton fetus in a frank or complete breech presentation at term (≥37 weeks). The trial found a substantial reduction in risk of adverse perinatal outcome, a composite measure of perinatal or neonatal mortality or serious neonatal morbidity, excluding lethal congenital anomalies, with a policy of planned caesarean [17 of 1039 (1.6%) vs 52 of 1039 (5.0%); relative risk (RR) 0.33, 95% CI 0.19–0.56, P < 0.001].2

Much of the concern around planning a vaginal birth for a singleton fetus in breech presentation at or near term has been the worry that the after-coming head of the breech may become entrapped during a vaginal delivery.4–6 That is, the body of the fetus might deliver vaginally without undue difficulty, but the delivery of the head may not follow immediately, either because the pelvis is too small, the fetal head is deflexed, or because the cervix is not completely dilated. Little concern has been expressed about planning a vaginal birth for a fetus in breech presentation, because of the worry that difficulties might arise during the labour. This may be because the monitoring of a breech labour is not dissimilar to the monitoring of a cephalic labour and if problems arise, one can proceed relatively easily to caesarean, unless in the case of a breech presentation, the fetus is already partially delivered. If a policy of planned caesarean for the singleton fetus in breech presentation at term was to reduce the risk of adverse perinatal outcome by avoiding problems associated with labour, this would suggest that a policy of planned caesarean might also be useful in some situations of cephalic presentation where there is a similar risk of labour problems.

We therefore wished to determine if the decreased risk of adverse perinatal outcome with a policy of planned caesarean, compared with a policy of planned vaginal birth, in the Term Breech Trial, was due to a decrease in risk of adverse outcome due to labour or due to delivery.

METHODS

Women were eligible for the Term Breech Trial if they had a singleton live fetus in a frank or complete breech presentation at term (≥37 weeks of gestation). The details of the eligibility criteria have been published previously.2 The study was approved by the research ethics committees at participating centres and women gave informed consent before being enrolled in the study. Randomisation was centrally controlled at the University of Toronto Maternal Infant and Reproductive Health Research Unit, with a computerised randomisation program accessible by means of a touch-tone telephone.

Women enrolled in the study were randomly allocated to either the planned caesarean or the planned vaginal birth group. If randomised to the planned caesarean group, a caesarean was scheduled for ≥38 weeks of gestation. If the woman was in labour at the time of randomisation, the caesarean was undertaken as soon as possible. Immediately prior to caesarean, the fetal presentation was reassessed and if cephalic, a vaginal birth was planned. If randomised to the planned vaginal birth group, management was expectant until spontaneous labour began, unless an indication to induce labour (e.g. post-term pregnancy), or undertake a caesarean (e.g. footling breech presentation) developed. The protocol for management during labour has been previously reported.2 Babies in breech presentation, who were delivered vaginally, were attended by a clinician experienced in vaginal breech birth. This was a clinician who considered him/herself to be skilled and experienced at vaginal breech delivery, confirmed by the individual's Head of Department.

Actual method of delivery was defined as either prelabour caesarean, caesarean during early labour (contractions less frequent than every 5 minutes or if more frequent than every 5 minutes, cervix was less than 3 cm dilated and less than 80% effaced), caesarean during active labour (contractions more frequent than every 5 minutes and cervix 3 cm or more dilated or 80% or more effaced) or vaginal birth.

Adverse perinatal outcome in the Term Breech Trial was defined as one or more of the following: perinatal or neonatal mortality at less than 28 days of age (excluding lethal congenital anomalies), or one or more of the following measures of serious neonatal morbidity: birth trauma, which included subdural haematoma, intracerebral or intraventricular haemorrhage, spinal cord injury, basal skull fracture, peripheral nerve injury present at discharge from hospital or clinically significant genital injury; seizures occurring at less than 24 hours of age or requiring two or more drugs to control them; Apgar score of less than 4 at 5 minutes; cord blood base deficit of at least 15; hypotonia for at least 2 hours; stupor, decreased response to pain or coma; intubation and ventilation for at least 24 hours; tube feeding for four days or more; or admission to the neonatal intensive care unit for longer than four days.2

For those infants with an adverse perinatal outcome, the outcome was assigned to one of four groups: due to labour, due to delivery, unrelated to either labour or delivery, or unexplained, using the following guidelines: the outcome was considered to be due to labour if there was evidence of hypoxia (any one or combination of low Apgar score at 5 minutes, low cord blood pH, high cord blood base deficit, seizures) with or without documented fetal heart rate abnormality, and no evidence of either a difficult delivery or birth trauma; the outcome was considered to be due to delivery if there was evidence of a difficult delivery, or if the infant had birth trauma; the outcome was considered to be unrelated to either labour or delivery if there was another reason for the outcome, such as a major congenital anomaly, or an intrauterine death which probably occurred prior to randomisation; all other outcomes were considered unexplained. Infants that suffered a significant genital injury that was noted during the second stage of labour but prior to delivery were considered to have had an adverse outcome due to labour. The assignment of outcomes to one or another category was made by an experienced obstetrician who was masked to allocation group.

Demographic, labour and delivery details, as well as neonatal outcome data, were tabulated for those infants with an adverse perinatal outcome, that is, for those who died or had one or more measures of serious neonatal morbidity, excluding lethal congenital anomalies, according to whether the outcome was considered to be due to labour, due to delivery, unrelated to either labour or delivery or unexplained. Countries were categorised according to their perinatal mortality rate as reported in 1996 by the World Health Organisation [low (≤20/1000) vs high (>20/1000)].7 Countries with a low perinatal mortality rate were Australia, Canada, Chile, Denmark, Finland, Germany, Israel, the Netherlands, New Zealand, Poland, Portugal, Romania, Switzerland, the United Kingdom, the USA and Yugoslavia. Countries with a high perinatal mortality rate were Argentina, Brazil, Egypt, India, Jordan, Mexico, Pakistan, Palestine, South Africa and Zimbabwe.7

Baseline characteristics, which were previously reported by randomised group,2 were also reported descriptively by actual method of delivery. Outcomes due to labour, due to delivery, unrelated to either labour or delivery or unexplained were compared between the planned caesarean and the planned vaginal birth groups, according to intention to treat, by means of Fisher's exact test. A two-sided P value of <0.05 indicated statistical significance. Outcomes were also compared descriptively by actual method of delivery. All analyses were performed using Statistical Analyses Software Release 8.2 (SAS, Cary, North Carolina).

RESULTS

Of the 2088 women from 121 centres in 26 countries enrolled in the Term Breech Trial, entry and outcome data were received for 2083 women, of whom 1041 were randomised to the planned caesarean group and 1042 were randomised to the planned vaginal birth group.2 Baseline characteristics were similar in the planned caesarean and planned vaginal birth groups.2 Baseline characteristics by actual method of delivery are reported in Table 1. Women having a prelabour caesarean were more likely to be 30 years of age or older, more likely to have had intact membranes, more likely to have had a previous attempt at external cephalic version and more likely to have been from a country with a low national perinatal mortality rate than women having other methods of delivery. Women having a vaginal birth were less likely to have been nulliparous and were more likely to have had an estimated fetal size or weight indicating a small baby than women having other methods of delivery. Of the 2083 women included in this study, 543 (26%) had a prelabour caesarean, 250 (12%) had a caesarean during early labour, 599 (29%) had a caesarean during active labour and 691 (33%) had a vaginal birth.

Table 1.  Baseline characteristics by actual method of delivery. Values are given as n (%).
CharacteristicsPrelabour CSCS during early labourCS during active labourVaginal birth
  • CS = caesarean section; early labour was defined as contractions less frequent than every 5 minutes or if more frequent than every 5 minutes, cervix was less than 3 cm dilated and less than 80% effaced; active labour was defined as contractions more frequent than every 5 minutes and cervix 3 cm or more dilated or 80% or more effaced; MRI = magnetic resonance imaging; CT = computed tomography.

  • *

    If the clinical and ultrasonography estimates of fetal size differed (e.g. the estimated size of the fetus clinically was small but by ultrasonography ≥3000 g or the estimated size of the fetus clinically was average but by ultrasonography <3000 g), the fetus was regarded as average size or ≥3000 g.

  • The country's national perinatal mortality rate was categorised as low [≤20/1000] or high [>20/1000] as reported in 1996 by the World Health Organisation.7 Countries with a low perinatal mortality rate were Australia, Canada, Chile, Denmark, Finland, Germany, Israel, the Netherlands, New Zealand, Poland, Portugal, Romania, Switzerland, the United Kingdom, the USA and Yugoslavia. Countries with a high perinatal mortality rate were Argentina, Brazil, Egypt, India, Jordan, Mexico, Pakistan, Palestine, South Africa and Zimbabwe.

Number543 (26)250 (12)599 (29)691 (33)
 
Maternal age
≥30 years203 (37)67 (27)183 (31)217 (31)
<30 years340 (63)183 (73)416 (69)474 (69)
 
Parity
0315 (58)132 (53)349 (58)296 (43)
1–4206 (38)102 (41)212 (35)348 (50)
>422 (4.1)16 (6.4)38 (6.3)47 (6.8)
 
Gestational age ≥41weeks32 (5.9)16 (6.4)39 (6.5)45 (6.5)
Diabetes16 (3.0)7 (2.8)7 (1.2)8 (1.2)
Uterine anomalies8 (1.5)4 (1.6)3 (0.5)3 (0.4)
Hypertension31 (5.7)6 (2.4)32 (5.3)32 (4.6)
In labour at randomisation0157 (63)356 (59)377 (55)
Membranes ruptured at randomisation30 (5.5)63 (25)189 (32)204 (30)
 
Type of breech at randomisation
Frank342 (63)148 (59)360 (60)442 (64)
Complete178 (33)89 (36)210 (35)225 (33)
Uncertain23 (4.2)13 (5.2)29 (4.8)24 (3.5)
 
Estimated fetal size or weight*
Average size or ≥3000 g358 (66)153 (61)409 (68)382 (55)
Small size and <3000 g185 (34)97 (39)189 (32)308 (45)
 
Method of estimating fetal size or weight
Clinical only136 (25)95 (38)280 (47)334 (48)
Ultrasonography (±clinical)407 (75)155 (62)319 (53)357 (52)
 
Method of assessing adequacy of pelvis
Clinical only477 (88)233 (93)548 (91)632 (91)
X-ray, MRI and/or CT (±clinical)66 (12)17 (6.8)51 (8.5)59 (8.5)
 
Method of assessing attitude of fetal head
Clinical only107 (20)70 (28)208 (35)260 (38)
X-ray and/or ultrasonography(±clinical)436 (80)180 (72)391 (65)431 (62)
 
Previous CS14 (2.6)11 (4.4)14 (2.3)15 (2.2)
Previous attempt at external cephalic version181 (33)38 (15)103 (17)126 (18)
 
National perinatal mortality rate
Low (≤20/1000)363 (67)114 (46)270 (45)280 (41)
High (>20/1000)180 (33)136 (54)329 (55)411 (59)

Excluding lethal anomalies, there were 69 infants in the Term Breech Trial who either died or had one or more measures of serious neonatal morbidity. Of these, 25 (36%) were classified as being due to labour (Table 2), 26 (38%) were classified as being due to delivery (Table 3), 6 (8.7%) were classified as being due to neither labour nor delivery (Table 4) and 12 (17%) were classified as unexplained (Table 5).

Table 2.  Details of outcomes due to labour.
National PMR of country§Planned method of deliveryActual method of deliveryDemographic and delivery detailsNeonatal outcome
  • PMR = perinatal mortality rate; VB = vaginal birth; CS = caesarean section; early labour was defined as contractions less frequent than every 5 minutes or if more frequent than every 5 minutes, cervix was less than 3 cm dilated and less than 80% effaced; active labour was defined as contractions more frequent than every 5 minutes and cervix 3 cm or more dilated or 80% or more effaced; P = Parity; GA = Gestational age at randomisation (weeks); cEFM = continuous electronic fetal heart rate monitoring; iEFM = intermittent electronic fetal heart rate monitoring; IA = Intermittent auscultation; ob = obstetrician; ob(t) = obstetrician in training; exp = experienced according to the a priori definition in the Term Breech Trial which was someone who considered him/herself to be experienced at vaginal breech delivery with confirmation from the Head of Department; FHRabn = fetal heart rate abnormality; labind = labour induction with oxytocin or prostaglandins; labaug = labour augmentation with oxytocin or prostaglandins; BW = birthweight; min = minute; hrs = hours; BD = base deficit; RD = respiratory distress; NICU = neonatal intensive care unit.

  • *

    Labour was considered prolonged if there was 18 or more hours from the onset of active labour to full dilatation, 2 or more hours from full dilatation to start of pushing, or 1.5 or more hours from start of pushing to delivery.

  • Fetal presentation at delivery.

  • §

    High is >20/1000 and low is ≤20/1000.7

  • Significant genital injury was classified as due to labour if it was noted during labour and before the delivery.

HighVBCS during active labourP = 0; GA < 41; cEFM, spinal; frank breech; clinician: ob/expBW = 3270 g; 5 min Apgar = 8; BD = 28; cord pH = 6.94; RD; seizure at <1 day and having 1 drug; NICU for 1 day
HighVBVBP ≥ 1; GA < 41; iEFM; FHRabn; complete breech; clinician: ob/expBW = 2700 g; stillbirth (fetal heart tones disappeared before a CS could be started)
HighCSCS during active labourP = 0; GA < 41; IA; spinal; FHRabn; frank breech; clinician: ob/expBW = 2450 g; 5 min Apgar = 8; BD = 15; cord pH = 7.04; RD; ventilation for 3 days; NICU for 3 days
HighVBVB: forcepsP = 0; GA < 41; IA; complete breech; clinician: ob/expBW = 2240 g; 5 min Apgar = 6; BD = 19.6; cord pH = 6.93; tube feeding for <1 day
HighVBVB: forcepsP = 0; GA ≥ 41; cEFM; complete breech; clinician: ob/expBW = 2580 g; 5 min Apgar = 10; BD = 17.1; cord pH = 7.12
HighCSCS during active labourP = 0; GA < 41; IA; spinal; frank breech; clinician: ob/expBW = 2525 g; 5 min Apgar = 9; BD = 15.9; cord pH = 7.09
LowVBVBP = 0; GA < 41; iEFM; FHRabn; labaug; complete breech; clinician: ob/expBW = 3900 g; 5 min Apgar = 6; BD = 15; cord pH = 7.16; RD; hypotonia for <1 day; stupor or decreased response to pain
LowVBCS during early labourP ≥ 1; GA < 41; cEFM; FHRabn; labind; labaug; complete breech; clinician: ob/expBW = 3120 g; 5 min Apgar = 10; IC/IVH; hypotonia for 4 days; hyperalert, drowsy or lethargic; NICU for 2 days
LowVBVBP = 0; GA ≥ 41; iEFM; FHRabn; labaug; frank breech; clinician: ob/expBW = 2965 g; stillbirth (fetal heart tones disappeared during second stage of labour too late to undertake a CS)
LowVBVBP = 0; GA < 41; IA; labaug; frank breech; clinician: ob/expBW = 2759 g; 5 min Apgar = 4; BD = 14.8; cord pH = 7.00; seizures at <1 day and having 1 drug; hyperalert, drowsy or lethargic; NICU for 7 days
LowVBCS during active labourP ≥ 1; GA < 41; cEFM; FHRabn; labind; epidural; prolonged labour;* frank breech; clinician: ob/expBW = 4069 g; 5 min Apgar = 8; BD = 14; cord pH = 7.03; RD; significant genital injury
LowVBVBP = 0; GA ≥ 41; cEFM; FHRabn; labind; epidural; frank breech; clinician: ob/expBW = 2835 g; 5 min Apgar = 3; BD = 20; cord pH = 7.04; RD; seizures at <1 day and having 2 drugs; hypotonia for 1 hr; hyperalert, drowsy or lethargic; ventilation for 17 days; tube feeding for 15 days; NICU for 2 days
LowVBVB: forcepsP = 0; GA < 41; cEFM; labaug; epidural; frank breech; clinician: ob(t)/expBW = 2560 g; 5 min Apgar = 4; cord pH = 7.04; RD; hypotonia for 2 days; ventilation for <1 day; tube feeding for 1 day; NICU for <1 day
LowVBVBP ≥ 1; GA < 41; cEFM; labind; prolonged labour;* frank breech; clinician: ob(t)/expBW = 3600 g; 5 min Apgar = 3; cord pH = 7.30
LowVBVBP ≥ 1; GA < 41; IA; cephalic; clinician: midwife/no expBW = 4720 g; 5 min Apgar = 3
LowVBCS during active labourP = 0; GA < 41; cEFM; FHRabn; spinal; complete breech; clinician: ob(t)/no expBW = 2860 g; 5 min Apgar = 8; BD = 15.8; cord pH = 7.10
LowVBVBP ≥ 1; GA < 41; cEFM; FHRabn; epidural; labaug; frank breech; clinician: ob/expBW = 3962 g; 5 min Apgar = 4; BD = 16.5; cord pH = 6.9; RD; hypotonia for <1 hr, ventilation for <1 day; NICU for <1 day
LowVBVBP ≥ 1; GA < 41; cEFM; epidural; labaug, complete breech; clinician: ob/expBW = 3503 g; 5 min Apgar = 6; BD = 16; cord pH = 6.93; RD
LowVBVB: forcepsP = 0; GA < 41; cEFM; epidural; prolonged labour;* labaug; frank breech; clinician: ob/expBW = 3030 g; 5 min Apgar = 3; BD = 5.1; cord pH = 7.32; RD; NICU for <1 day
LowVBCS during active labourP ≥ 1; GA < 41; cEFM; FHRabn; labind; epidural; labaug; complete breech; clinician: ob/expBW = 3255 g; 5 min Apgar = 8; BD = 21.6; cord pH = 6.92; NICU for 3 days
LowCSCS during active labourP = 0; GA < 41; cEFM; epidural; prolonged labour;* labaug; frank breech; clinician: ob/expBW = 3572 g; 5 min Apgar = 9; significant genital injury
LowVBCS during active labourP ≥ 1; GA < 41; iEFM; epidural; FHRabn; prolonged labour;* frank breech; clinician: ob(t)/no expBW = 2790 g; 5 min Apgar = 10; BD = 14.3; cord pH = 7.15; tube feeding for 5 days
LowVBCS during active labourP ≥ 1; GA < 41; cEFM; FHRabn; frank breech; clinician: ob(t)/expBW = 3520 g; 5 min Apgar = 7; BD = 11; cord pH = 7.07; RD; seizure at 14 days and having 1 drug; tube feeding for 6 days; NICU
LowVBVBP ≥ 1; GA < 41; cEFM; epidural; FHRabn; complete breech; clinician: ob/expBW = 2700 g; 5 min Apgar = 7; BD = 13.5; cord pH = 7.27; RD; hypotonia for 4 days; ventilation for 1 day; tube feeding for 2 days; NICU for 22 days
LowVBVBP = 0; GA < 41; iEFM; labaug; complete breech; clinician: ob/expBW = 3100 g; 5 min Apgar = 9; BD = 15.2; cord pH = 7.11
Table 3.  Details of outcomes due to delivery.
National PMR of country§Planned method of deliveryActual method of deliveryDemographic and delivery detailsNeonatal outcome
  • Please refer to Table 2 for abbreviations.

  • *

    Labour was considered prolonged if there was 18 or more hours from the onset of active labour to full dilatation, 2 or more hours from full dilatation to start of pushing, or 1.5 or more hours from start of pushing to delivery.

  • Fetal presentation at delivery.

  • Brachial plexus injuries were present at discharge from hospital.

  • §

    High is >20/1000 and low is ≤20/1000.7

HighCSCS during active labourP ≥ 1; GA < 41; IA; epidural; difficult delivery; complete breech; clinician: ob/expBW = 3150 g; 5 min Apgar = 10; BD = 17.8; cord pH = 7.17
HighVBVBP ≥ 1; GA < 41; cEFM; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3500 g; 5 min Apgar = 3; BD = 32.6; cord pH = 6.70; RD; brachial plexus injury; hypotonia for 11 days; coma; ventilation for 7 days; tube feeding for 7 days; NICU for 9 days
HighVBVBP = 0; GA < 41; iEFM; epidural; labaug; difficult delivery; complete breech; clinician: ob/expBW = 3600 g; 5 min Apgar = 6; BD = 15.3; cord pH = 7.10; RD; hypotonia for <1 day; coma; ventilation for <1 day; NICU for 2 days
HighVBVBP = 0; GA < 41; IA; labaug; difficult delivery; frank breech; clinician: ob/expBW = 2400 g; stillbirth
HighCSPrelabour CSP = 0; GA <41; spinal; complete breech; clinician: ob/expBW = 2540 g; 5 min Apgar = 10; RD; basal skull fracture; tube feeding for <1 day
HighCSVBP = 0; GA < 41; iEFM; difficult delivery; frank breech; clinician: ob/expBW = 2550 g; stillbirth
HighVBVB: forcepsP ≥ 1; GA < 41; IA; labaug; difficult delivery; frank breech; clinician: ob(t)/expBW = 3500 g; 5 min Apgar = 0, hypotonia for <1 hr; stupor/decreased response to pain; neonatal death at <1 hr—baby had a small head, low set ears and deep set eyes
HighVBVBP = 0; GA ≥ 41; IA; labind; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3000 g; stillbirth
HighVBVBP = 0; GA < 41; IA; difficult delivery; complete breech; clinician: ob/expBW = 2115 g; 5 min Apgar = 7; seizures at <1 day and having 1 drug
HighVBVBP ≥ 1; GA < 41; IA; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3420 g; 5 min Apgar = 3; RD; brachial plexus injury; seizures at <1 day and having 3 drugs; hyperalert, drowsy or lethargic; ventilation for <1 day; tube feeding for <1 day
HighVBVBP = 0; GA < 41; IA; difficult delivery; complete breech; clinician: ob(t)/expBW = 2635 g; 5 min Apgar = 6; RD; hypotonia for <1 day; tube feeding for 1 day
HighVBVBP = 0; GA < 41; IA; difficult delivery; complete breech; clinician: ob(t)/expBW = 3050 g; stillbirth
HighCSVBP = 0; GA < 41; IA; frank breech; clinician: ob(t)/expBW = 2390 g; 5 min Apgar = 7; brachial plexus injury; tube feeding for 1 day
HighVBVBP = 0; GA < 41; IA; epidural; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3050 g; 5 min Apgar = 2
HighCSVBP = 0; GA < 41; IA; prolonged labour;* difficult delivery; footling breech; clinician: ob/expBW = 2790 g; 5 min Apgar = 1; cord pH = 7.30; RD; hypotonia for <1 day; NICU for 9 days
HighCSCS during active labourP ≥ 1; GA < 41; IA; spinal; difficult delivery; complete breech; clinician: ob/no expBW = 3100 g; 5 min Apgar = 6; spinal cord injury; hypotonia for 1 day
HighVBVBP ≥ 1; GA < 41; iEFM, epidural; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3340 g; 5 min Apgar = 2; RD; brachial plexus injury; hypotonia for <1 day
HighCSCS during active labourP = 0; GA ≥ 41; IA; spinal; frank breech; clinician: ob/no expBW = 3300 g; 5 min Apgar = 8; brachial plexus injury
HighVBVBP ≥ 1; GA < 41; iEFM; difficult delivery; frank breech; clinician: ob/no expBW = 2310 g; 5 min Apgar = 6; BD = 13; cord pH = 7.31; RD; hypotonia for <1 day; tube feeding for 1 day; NICU for 1 day
LowVBCS during active labour following attempt at VBP = 0; GA < 41; cEFM; labind; epidural, FHRabn; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3370 g; 5 min Apgar = 0, BD = 14; cord pH = 7.09; RD; seizures at <1 day and having 2 drugs; hypotonia for 3 days; coma; ventilation for 3 days; NICU for 3 days; neonatal death at 3 days
LowVBVBP = 0; GA < 41; iEFM; epidural; FHRabn; labaug; frank breech; clinician: ob/expBW = 3450 g; 5 min Apgar = 10; BD = 5.9; cord pH = 7.17; significant genital injury
LowVBVBP ≥ 1; GA < 41; cEFM; difficult delivery; frank breech; clinician: ob(t)/no expBW = 3360 g; 5 min Apgar = 4; BD = 9.1; cord pH = 7.14; RD; seizures at <1 day and having 2 drugs; hyperalert, drowsy or lethargic; ventilation for <1 day; tube feeding for 3 days; NICU for 2 days
LowVBVBP ≥ 1; GA ≥ 41; IA; labind; difficult delivery; footling breech; clinician: ob(t)/expBW = 3350 g; 5 min Apgar = 3; BD = 5.5; cord pH = 7.21; tube feeding for 1 day
LowVBVBP = 0; GA < 41; cEFM; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3910 g; 5 min Apgar = 10; BD = 16.7; cord pH = 7.15
LowVBVBP ≥ 1; GA <41; cEFM; labaug; complete breech; clinician: ob/expBW = 3480 g; 5 min Apgar = 9; cord pH = 7.28; brachial plexus injury; hypotonia for 3 days; hyperalert, drowsy or lethargic; NICU for 3 days
LowVBVBP = 0; GA < 41; iEFM; labind; labaug; difficult delivery; frank breech; clinician: ob/expBW = 3510 g; 5 min Apgar = 6; BD = 4.4; cord pH = 7.37; RD; brachial plexus injury; ventilation for <1 day; tube feeding for 2 days
Table 4.  Details of outcomes unrelated to either labour or delivery.
National PMR of country§Planned method of deliveryActual method of deliveryDemographic and delivery detailsNeonatal outcome
  • VSD = ventricular septal defect; PDA = patent ductus arteriosus. Please refer to Table 2 for the other abbreviations.

  • Fetal presentation at delivery.

  • §

    High is >20/1000 and low is ≤20/1000.7

HighVBVBP ≥ 1; GA ≥ 41; labaug; cephalic; clinician: ob(t)/no expBW = 3650 g; stillbirth (probably before enrollment)
HighCSCS during active labourP ≥ 1; GA < 41; IA; epidural; frank breech; clinician: ob(t)/no expBW = 3300 g; 5 min Apgar = 10; tube feeding for 63 days; NICU for 62 days; anomaly (intestinal obstruction)
HighVBCS during active labourP ≥ 1; GA < 41; FHRabn; cEFM; epidural; complete breech; clinician: ob(t)/expBW = 4020 g; 5 min Apgar = 8; RD; hypotonia for 17 days; tube feeding for 10 days; anomaly (Down's Syndrome)
HighCSCS during active labourP = 0; GA < 41; IA; FHRabn; frank breech; clinician: ob(t)/no expBW = 2805 g; 5 min Apgar = 7; seizures at 14 days and having 1 drug; anomaly (ruptured myelomeningocele); neonatal death at 21 days
LowVBCS during early labourP ≥ 1; GA < 41; cEFM; labind; epidural; labaug; frank breech; clinician: ob/expBW = 2620 g; 5 min Apgar = 9; RD; NICU for 7 days; anomaly (VSD and PDA)
LowVBVBP ≥ 1; GA < 41; iEFM; labaug; clinician: ob/exp Twin A: frank breech Twin B: frank breechTwin A: BW = 1150 g; stillbirth of a preterm twin (probably before enrollment) Twin B: BW = 2300 g; 5 min Apgar = 7; RD; hypotonia for <1 day; hyperalert, drowsy or lethargic; NICU for 2 days; neonatal sepsis or meningitis
Table 5.  Details of outcomes categorised as unexplained.
National PMR of country§Planned method of deliveryActual method of deliveryDemographic and delivery detailsNeonatal outcome
  • IC/IVH = intracranial or intraventricular haemorrhage. Please refer to Table 2 for the other abbreviations.

  • *

    Labour was considered prolonged if there was 18 or more hours from the onset of active labour to full dilatation, 2 or more hours from full dilatation to start of pushing, or 1.5 or more hours from start of pushing to delivery.

  • Fetal presentation at delivery.

  • §

    High is >20/1000 and low is ≤20/1000.7

HighCSPrelabour CSP = 0; GA < 41; spinal; frank breech; clinician: ob/expBW = 2920 g; 5 min Apgar = 10; BD = 15.1; cord pH = 7.18
HighVBVBP = 0; GA < 41; IA; labind; labaug; complete breech; clinician: ob(t)/expBW = 2000 g; 5 min Apgar = 8; neonatal death (baby discharged home well and died during sleep on day 2)
HighVBVB: forcepsP = 0; GA < 41; IA; labaug; frank breech; clinician: ob(t)/expBW = 2500 g; 5 min Apgar = 9; neonatal death (baby discharged home well; died on day 5 after developing severe vomiting and diarrhoea)
HighCSPrelabour CSP ≥ 1; GA < 41; frank breech; clinician: ob(t)/expBW = 2800 g; 5 min Apgar = 7; RD; seizures on day 3 and having 2 drugs; hyperalert, drowsy or lethargic; ventilation at <1 day; NICU for< 1 day
HighCSPrelabour CSP ≥ 1; GA < 41; uncertain type of breech; clinician: ob/expBW = 2300 g; 5 min Apgar = 7; RD; ventilation for 1 day; neonatal death on day 1
HighVBVB: forcepsP≥1; GA < 41; IA; frank breech; clinician: ob/expBW = 2500 g; 5 min Apgar = 7; RD; hypotonia for <1 day; hyperalert, drowsy or lethargic; neonatal death (died at <1 day)
HighVBCS during active labourP = 0; GA < 41; IA; labaug; prolonged labour;* frank breech; clinician: ob/expBW = 2590 g; 5 min Apgar = 9; RD; ventilation for 2 days; tube feeding for 3 days; NICU for 5 days
HighVBVBP = 0; GA < 41; IA; frank breech; clinician: ob(t)/expBW = 2700 g; 5 min Apgar = 7; RD; hypotonia for <1 day; neonatal death at <1 day
HighCSPrelabour CSP ≥ 1; GA < 41; spinal; complete breech; clinician: ob/expBW = 3200 g; 5 min Apgar = 10; BD = 6.9; cord pH = 7.31; RD; tube feeding for 5 days; NICU for 5 days
LowVBCS during active labourP = 0; GA < 41; cEFM; epidural, FHRabn; labaug; prolonged labour;* complete breech; clinician: ob(t)/no expBW = 4160 g; 5 min Apgar = 8; BD = 6.8; cord pH = 7.26; RD; tube feeding for 4 days
LowCSCS during early labourP ≥ 1; GA < 41; cEFM; spinal; frank breech; clinician: ob/expBW = 3900 g; 5 min Apgar = 9; BD = 6.6; cord pH = 7.25; RD; NICU for 7 days
LowVBVBP ≥ 1; GA < 41; iEFM; labaug; frank breech; clinician: ob/expBW = 3250 g; 5 min Apgar = 9; BD = 4.5; cord pH = 7.36; RD; IC/IVH; hypotonia for 2 days; hyperalert, drowsy, or lethargic; NICU for 4 days

There was a lower risk of adverse perinatal outcome due to labour in the planned caesarean group compared with the planned vaginal birth group [3 of 1039 (0.3%) vs 22 of 1039 (2.1%); RR 0.14, 95% CI 0.04–0.45, P < 0.001]. There was also a lower risk of adverse perinatal outcome due to delivery in the planned caesarean versus planned vaginal birth groups [7 of 1039 (0.7%) vs 19 of 1039 (1.8%); RR 0.37, 95% CI 0.16–0.87, P= 0.03]. There was no significant difference between the planned caesarean and the planned vaginal birth groups in risk of adverse perinatal outcome unrelated to either labour or delivery [2 of 1039 (0.2%) vs 4 of 1039 (0.4%); RR 0.50, 95% CI 0.09–2.7, P= 0.69], or in risk of adverse perinatal outcome that was unexplained [5 of 1039 (0.5%) vs 7 of 1039 (0.7%); RR 0.71, 95% CI 0.23–2.2, P= 0.77] (Table 6).

Table 6.  Adverse perinatal outcome by planned method of delivery. Values are given as n (%) and RR [95% CI].
Outcome§Planned caesarean section (n= 1039)Planned vaginal birth (n= 1039)RR [95% CI]
  • §

    Excludes lethal congenital anomalies.

Any adverse perinatal outcome17 (1.6)52 (5.0)0.33 [0.19–0.56]
Outcome due to labour3 (0.3)22 (2.1)0.14 [0.04–0.45]
Outcome due to delivery7 (0.7)19 (1.8)0.37 [0.16–0.87]
Outcome unrelated to labour or delivery2 (0.2)4 (0.4)0.50 [0.09–2.7]
Outcome unexplained5 (0.5)7 (0.7)0.71 [0.23–2.2]

The risk of adverse perinatal outcome due to labour was highest for those who actually delivered vaginally [15 of 689 (2.2%)], somewhat lower for those who delivered by caesarean during active labour [9 of 598 (1.5%)] and lowest for those who delivered by caesarean during early labour [1 of 249 (0.4%)] or by caesarean before labour [0 of 542 (0%)]. The risk of adverse perinatal outcome due to delivery was highest for those who delivered vaginally [21 of 689 (3.1%)], and lower for those who delivered by caesarean during active labour [4 of 598 (0.7%)], by caesarean during early labour [0 of 249 (0%)] and by caesarean before labour [1 of 542 (0.2%)]. The risk of adverse perinatal outcome that was unrelated to either labour or delivery, or was unexplained, was similar for those who delivered vaginally, by caesarean during active labour, by caesarean during early labour or by caesarean before labour (Table 7).

Table 7.  Adverse perinatal outcome by actual method of delivery. Values are given as n (%).
Outcome§Prelabour caesarean section (n= 542)Caesarean section during early labour (n= 249)Caesarean section during active labour (n= 598)Vaginal birth (n= 689)
  • §

    Excludes lethal congenital anomalies; early labour was defined as contractions less frequent than every 5 minutes or if more frequent than every 5 minutes, cervix was less than 3 cm dilated and less than 80% effaced; active labour was defined as contractions more frequent than every 5 minutes and cervix 3 cm or more dilated or 80% or more effaced.

Any adverse perinatal outcome5 (0.9)3 (1.2)18 (3.0)43 (6.2)
Outcome due to labour0 (0.0)1 (0.4)9 (1.5)15 (2.2)
Outcome due to delivery1 (0.2)0 (0.0)4 (0.7)21 (3.1)
Outcome unrelated to labour or delivery0 (0.0)1 (0.4)3 (0.5)2 (0.3)
Outcome unexplained4 (0.7)1 (0.4)2 (0.3)5 (0.7)

DISCUSSION

We found that planned caesarean was associated with a significantly reduced risk of both adverse perinatal outcome that was due to labour as well as adverse perinatal outcome that was due to delivery compared with planned vaginal birth. Therefore, the benefits of a policy of planned caesarean shown in the Term Breech Trial appeared to be due to both the avoidance of labour and the avoidance of vaginal breech birth. These findings raise the possibility that planned caesarean may be useful in other situations of cephalic presentation where labour may be associated with problems. This study also found that vaginal birth was associated with the highest risk of adverse perinatal outcome, whereas prelabour caesarean and caesarean during early labour were associated with the lowest risks of adverse perinatal outcome due to either labour or delivery. Thus, from the baby's perspective, a prelabour caesarean or a caesarean during early labour are better approaches to delivery if there is a singleton fetus in breech presentation at term. These findings are consistent with the findings of observational studies which have found better outcomes for the singleton fetus in breech presentation at term following elective caesarean, compared with emergency caesarean.8–12

We recognise that the categorisation of outcomes may not have been correct in some instances. For example, we did not have information on types of fetal heart rate changes or on scalp pH measurements. Also, some clinical observations and autopsy information were limited or unavailable. The criteria used to determine if the outcome was due to labour may have included outcomes that were actually due to the delivery as outcomes were only categorised as being due to the delivery if there was evidence of birth trauma or if the clinician had noted difficulty with the delivery. We attempted to avoid bias in the categorisation of outcomes by masking the individual, who undertook this part of the study, to the planned method of delivery. However, it was not possible to mask this individual to actual method of delivery and this may have been a source of bias. To compensate for this, we reported details of all adverse perinatal outcomes so that others would be able to recategorise and draw their own conclusions.

It is interesting to note that there were more adverse outcomes that were categorised as being due to problems of labour in countries with a low national perinatal mortality rate, compared with countries with a high national perinatal mortality rate, whereas the reverse was found for outcomes due to delivery. Some of these differences may be due to misclassification, either because the fetus was less likely to be monitored continuously with electronic fetal heart rate monitoring or because the cord pH was less likely to be assessed in countries with a high national perinatal mortality rate. However, it is unlikely that difficult deliveries or birth trauma would be reported differently in countries with a high versus low national perinatal mortality rate. Further research is needed to explore the reasons for these differences.

In summary, our findings suggest that if a fetus is in breech presentation at term, planned caesarean will reduce the risk of adverse perinatal outcome due to either problems of labour or problems of delivery compared with planned vaginal birth. More specifically, the risk is lowest with prelabour caesarean or caesarean during early labour, whereas the risk is highest with vaginal birth.

Acknowledgements

This research was supported by the Canadian Institutes of Health Research (CIHR, previously the Medical Research Council of Canada), grant number MT-13884. Mary E. Hannah holds a CIHR Senior Scientist Award. The Data Coordinating Centre was supported by grants from the Centre for Research in Women's Health, Sunnybrook and Women's College Health Sciences Centre and the Department of Obstetrics and Gynaecology at the University of Toronto. The members of the Term Breech Trial Collaborative group are listed in Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR, for the Term Breech Trial Collaborative Group. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Lancet 2000;356:1735–1783.

Accepted 13 April 2004

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