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. Author manuscript; available in PMC: 2014 Sep 19.
Published in final edited form as: Cochrane Database Syst Rev. 2010 Jan 20;(1):CD007529. doi: 10.1002/14651858.CD007529.pub2

Comparison 1. Doppler ultrasound versus no Doppler ultrasound.

Outcome or subgroup title No. of studies No. of participants Statistical method Effect size
1 Any perinatal death after randomisation 16 10225 Risk Ratio (M-H, Fixed, 95% CI) 0.71 [0.52, 0.98]
 1.1 Singleton pregnancy 9 4661 Risk Ratio (M-H, Fixed, 95% CI) 0.59 [0.35, 1.01]
 1.2 Multiple pregnancy 1 1052 Risk Ratio (M-H, Fixed, 95% CI) 0.88 [0.32, 2.41]
 1.3 Singleton plus multiple pregnancies 2 2874 Risk Ratio (M-H, Fixed, 95% CI) 0.86 [0.49, 1.53]
 1.4 Not specified whether singleton or multiple pregnancies 4 1638 Risk Ratio (M-H, Fixed, 95% CI) 0.68 [0.36, 1.30]
2 Serious neonatal morbidity 3 Risk Ratio (M-H, Random, 95% CI) Subtotals only
 2.1 Singleton pregnancy 1 500 Risk Ratio (M-H, Random, 95% CI) 0.13 [0.02, 0.99]
 2.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Random, 95% CI) Not estimable
 2.3 Singleton plus multiple pregnancies 1 545 Risk Ratio (M-H, Random, 95% CI) 2.95 [0.31, 28.14]
 2.4 Not specified whether singleton or multiple pregnancies 1 53 Risk Ratio (M-H, Random, 95% CI) Not estimable
3 Stillbirth 15 9560 Risk Ratio (M-H, Fixed, 95% CI) 0.65 [0.41, 1.04]
 3.1 Singleton pregnancy 8 3996 Risk Ratio (M-H, Fixed, 95% CI) 0.61 [0.31, 1.19]
 3.2 Multiple pregnancy 1 1052 Risk Ratio (M-H, Fixed, 95% CI) 0.67 [0.11, 4.00]
 3.3 Singleton plus multiple pregnancy 2 2874 Risk Ratio (M-H, Fixed, 95% CI) 1.20 [0.40, 3.56]
 3.4 Not specified whether singleton or multiple pregnancies 4 1638 Risk Ratio (M-H, Fixed, 95% CI) 0.48 [0.19, 1.22]
4 Neonatal death 13 8167 Risk Ratio (M-H, Fixed, 95% CI) 0.81 [0.53, 1.24]
 4.1 Singleton pregnancy 7 2656 Risk Ratio (M-H, Fixed, 95% CI) 0.69 [0.31, 1.53]
 4.2 Multiple pregnancy 1 1052 Risk Ratio (M-H, Fixed, 95% CI) 1.01 [0.29, 3.46]
 4.3 Singleton plus multiple pregnancies 2 2874 Risk Ratio (M-H, Fixed, 95% CI) 0.76 [0.38, 1.50]
 4.4 Not specified whether singleton or multiple pregnancies 3 1585 Risk Ratio (M-H, Fixed, 95% CI) 1.00 [0.40, 2.53]
5 Any potentially preventable perinatal death* 16 10225 Risk Ratio (M-H, Fixed, 95% CI) 0.67 [0.46, 0.98]
 5.1 Singleton pregnancy 9 4661 Risk Ratio (M-H, Fixed, 95% CI) 0.58 [0.30, 1.13]
 5.2 Multiple pregnancy 1 1052 Risk Ratio (M-H, Fixed, 95% CI) 0.88 [0.32, 2.41]
 5.3 Singleton plus multiple pregnancies 2 2874 Risk Ratio (M-H, Fixed, 95% CI) 0.81 [0.38, 1.73]
 5.4 Not specified whether singleton or multiple pregnancies 4 1638 Risk Ratio (M-H, Fixed, 95% CI) 0.59 [0.29, 1.21]
6 Fetal acidosis 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 6.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 6.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 6.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 6.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
7 Apgar < 7 at 5 minutes 7 6321 Risk Ratio (M-H, Fixed, 95% CI) 0.92 [0.69, 1.24]
 7.1 Singleton pregnancy 4 2555 Risk Ratio (M-H, Fixed, 95% CI) 0.70 [0.45, 1.09]
 7.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 7.3 Singleton plus multiple pregnancies 2 2869 Risk Ratio (M-H, Fixed, 95% CI) 1.22 [0.78, 1.90]
 7.4 Not specified whether singleton or multiple pregnancies 1 897 Risk Ratio (M-H, Fixed, 95% CI) 0.93 [0.36, 2.39]
8 Caesarean section (elective and emergency) 14 7918 Risk Ratio (M-H, Fixed, 95% CI) 0.90 [0.84, 0.97]
 8.1 Singleton pregnancy 7 2929 Risk Ratio (M-H, Fixed, 95% CI) 0.84 [0.75, 0.95]
 8.2 Multiple pregnancy 1 526 Risk Ratio (M-H, Fixed, 95% CI) 0.96 [0.77, 1.19]
 8.3 Singleton plus multiple pregnancies 2 2794 Risk Ratio (M-H, Fixed, 95% CI) 0.95 [0.82, 1.10]
 8.4 Not specified whether singleton or multiple pregnancies 4 1669 Risk Ratio (M-H, Fixed, 95% CI) 0.93 [0.79, 1.10]
9 Caesarean section - elective 11 6627 Risk Ratio (M-H, Fixed, 95% CI) 1.07 [0.93, 1.22]
 9.1 Singleton pregnancy 6 1934 Risk Ratio (M-H, Fixed, 95% CI) 1.11 [0.90, 1.38]
 9.2 Multiple pregnancy 1 526 Risk Ratio (M-H, Fixed, 95% CI) 1.06 [0.77, 1.47]
 9.3 Singleton plus multiple pregnancies 2 2794 Risk Ratio (M-H, Fixed, 95% CI) 0.87 [0.67, 1.14]
 9.4 Not specified whether singleton or multiple pregnancies 2 1373 Risk Ratio (M-H, Fixed, 95% CI) 1.30 [0.96, 1.78]
10 Caesarean section - emergency 10 6175 Risk Ratio (M-H, Random, 95% CI) 0.81 [0.67, 0.98]
 10.1 Singleton pregnancy 5 1482 Risk Ratio (M-H, Random, 95% CI) 0.58 [0.43, 0.78]
 10.2 Multiple pregnancy 1 526 Risk Ratio (M-H, Random, 95% CI) 0.84 [0.57, 1.23]
 10.3 Singleton plus multiple pregnancies 2 2794 Risk Ratio (M-H, Random, 95% CI) 1.06 [0.88, 1.29]
 10.4 Not specified whether singleton or multiple pregnancies 2 1373 Risk Ratio (M-H, Random, 95% CI) 0.78 [0.60, 1.02]
11 Spontaneous vaginal birth 5 2504 Risk Ratio (M-H, Fixed, 95% CI) 1.04 [0.98, 1.10]
 11.1 Singleton pregnancy 2 576 Risk Ratio (M-H, Fixed, 95% CI) 1.07 [0.96, 1.18]
 11.2 Multiple pregnancy 1 526 Risk Ratio (M-H, Fixed, 95% CI) 1.03 [0.90, 1.19]
 11.3 Singleton plus multiple pregnancies 1 505 Risk Ratio (M-H, Fixed, 95% CI) 0.98 [0.86, 1.11]
 11.4 Not specified whether singleton or multiple pregnancies 1 897 Risk Ratio (M-H, Fixed, 95% CI) 1.06 [0.95, 1.19]
12 Operative vaginal birth 4 2813 Risk Ratio (M-H, Fixed, 95% CI) 0.95 [0.80, 1.14]
 12.1 Singleton pregnancy 3 1916 Risk Ratio (M-H, Fixed, 95% CI) 0.97 [0.78, 1.22]
 12.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 12.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 12.4 Not specified whether singleton or multiple pregnancies 1 897 Risk Ratio (M-H, Fixed, 95% CI) 0.92 [0.68, 1.25]
13 Induction of labour 10 5633 Risk Ratio (M-H, Random, 95% CI) 0.89 [0.80, 0.99]
 13.1 Singleton pregnancy 5 1784 Risk Ratio (M-H, Random, 95% CI) 0.79 [0.64, 0.97]
 13.2 Multiple pregnancy 1 526 Risk Ratio (M-H, Random, 95% CI) 1.10 [0.80, 1.50]
 13.3 Singleton plus multiple pregnancies 2 2794 Risk Ratio (M-H, Random, 95% CI) 0.95 [0.85, 1.05]
 13.4 Not specified whether singleton or multiple pregnancies 2 529 Risk Ratio (M-H, Random, 95% CI) 0.94 [0.72, 1.23]
14 Oxytocin augmentation 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 14.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 14.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 14.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 14.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
15 Neonatal resuscitation required 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 15.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 15.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 15.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 15.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
16 Infant requiring intubation/ventilation 6 3136 Risk Ratio (M-H, Random, 95% CI) 1.42 [0.87, 2.30]
 16.1 Singleton pregnancy 4 1539 Risk Ratio (M-H, Random, 95% CI) 2.89 [1.40, 5.96]
 16.2 Multiple pregnancy 1 1052 Risk Ratio (M-H, Random, 95% CI) 0.86 [0.59, 1.25]
 16.3 Singleton plus multiple pregnancies 1 545 Risk Ratio (M-H, Random, 95% CI) 1.25 [0.79, 1.98]
 16.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Random, 95% CI) Not estimable
17 Neonatal fitting/seizures 1 150 Risk Ratio (M-H, Fixed, 95% CI) 0.35 [0.01, 8.49]
 17.1 Singleton pregnancy 1 150 Risk Ratio (M-H, Fixed, 95% CI) 0.35 [0.01, 8.49]
 17.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 17.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 17.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
18 Preterm labour 2 626 Risk Ratio (M-H, Fixed, 95% CI) 1.12 [0.72, 1.75]
 18.1 Singleton pregnancy 1 150 Risk Ratio (M-H, Fixed, 95% CI) 1.03 [0.51, 2.07]
 18.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 18.3 Singleton plus multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 18.4 Not specified whether singleton or multiple pregnancies 1 476 Risk Ratio (M-H, Fixed, 95% CI) 1.18 [0.66, 2.11]
19 Infant respiratory distress syndrome (RDS) 1 107 Risk Ratio (M-H, Fixed, 95% CI) 1.06 [0.07, 16.48]
 19.1 Singleton pregnancy 1 107 Risk Ratio (M-H, Fixed, 95% CI) 1.06 [0.07, 16.48]
 19.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 19.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 19.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
20 Meconium aspiration 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 20.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 20.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 20.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 20.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
21 Neonatal admission to SCBU and/or NICU 12 9334 Risk Ratio (M-H, Fixed, 95% CI) 0.95 [0.89, 1.03]
 21.1 Singleton pregnancy 8 4511 Risk Ratio (M-H, Fixed, 95% CI) 0.92 [0.80, 1.06]
 21.2 Multiple pregnancy 1 1052 Risk Ratio (M-H, Fixed, 95% CI) 0.96 [0.88, 1.05]
 21.3 Singleton plus multiple pregnancies 2 2874 Risk Ratio (M-H, Fixed, 95% CI) 0.98 [0.83, 1.16]
 21.4 Not specified whether singleton or multiple pregnancies 1 897 Risk Ratio (M-H, Fixed, 95% CI) 1.00 [0.73, 1.37]
22 Hypoxic ischaemic encephalopathy 2 1045 Risk Ratio (M-H, Random, 95% CI) 0.65 [0.01, 33.07]
 22.1 Singleton pregnancy 1 500 Risk Ratio (M-H, Random, 95% CI) 0.09 [0.01, 1.64]
 22.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Random, 95% CI) Not estimable
 22.3 Singleton plus multiple pregnancies 1 545 Risk Ratio (M-H, Random, 95% CI) 4.91 [0.24, 101.79]
 22.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Random, 95% CI) Not estimable
23 Intraventricular haemorrhage 4 2008 Risk Ratio (M-H, Fixed, 95% CI) 1.42 [0.47, 4.30]
 23.1 Singleton pregnancy 3 1463 Risk Ratio (M-H, Fixed, 95% CI) 1.26 [0.38, 4.16]
 23.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 23.3 Singleton plus multiple pregnancies 1 545 Risk Ratio (M-H, Fixed, 95% CI) 2.95 [0.12, 71.99]
 23.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
24 Bronchopulmonary dysplasia 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 24.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 24.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 24.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 24.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
25 Necrotising enterocolitis 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 25.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 25.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 25.3 Single plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 25.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
26 Long-term infant neurodevelopmental outcome 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 26.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 26.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 26.3 Singleton plus multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 26.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
27 Women’s views of their care 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 27.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 27.2 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 27.3 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 27.4 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
28 Gestational age at birth 8 4066 Mean Difference (IV, Random, 95% CI) 0.21 [−0.02, 0.43]
 28.1 Singleton pregnancy 3 1043 Mean Difference (IV, Random, 95% CI) 0.54 [−0.00, 1.09]
 28.2 Multiple pregnancy 1 1052 Mean Difference (IV, Random, 95% CI) 0.10 [−0.24, 0.44]
 28.3 Singleton plus multiple pregnancies 1 545 Mean Difference (IV, Random, 95% CI) −0.20 [−0.81, 0.41]
 28.4 Not specified whether singleton or multiple pregnancies 3 1426 Mean Difference (IV, Random, 95% CI) 0.11 [−0.16, 0.38]
29 Birth weight 7 3887 Mean Difference (IV, Fixed, 95% CI) 31.33 [−8.70, 71.37]
 29.1 Singleton pregnancy 3 1916 Mean Difference (IV, Fixed, 95% CI) 49.34 [−0.62, 99.31]
 29.2 Multiple pregnancy 0 0 Mean Difference (IV, Fixed, 95% CI) Not estimable
 29.3 Singleton plus multiple pregnancies 1 545 Mean Difference (IV, Fixed, 95% CI) −48.0 [−192.49, 96.49]
 29.4 Not specified whether singleton or multiple pregnancies 3 1426 Mean Difference (IV, Fixed, 95% CI) 11.89 [−63.58, 87.36]
30 Length of infant hospital stay 3 1076 Std. Mean Difference (IV, Fixed, 95% CI) −0.28 [−0.40, −0.16]
 30.1 Singleton pregnancy 3 1076 Std. Mean Difference (IV, Fixed, 95% CI) −0.28 [−0.40, −0.16]
 30.2 Multiple pregnancy 0 0 Std. Mean Difference (IV, Fixed, 95% CI) Not estimable
 30.3 Singleton plus multiple pregnancies 0 0 Std. Mean Difference (IV, Fixed, 95% CI) Not estimable
 30.4 Not specified whether singleton or multiple pregnancies 0 0 Std. Mean Difference (IV, Fixed, 95% CI) Not estimable
31 Birth < 34 weeks (not prespecified) 2 976 Risk Ratio (M-H, Random, 95% CI) 2.04 [0.62, 6.69]
 31.1 Singleton pregnancy 1 500 Risk Ratio (M-H, Random, 95% CI) 1.17 [0.40, 3.42]
 31.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Random, 95% CI) Not estimable
 31.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Random, 95% CI) Not estimable
 31.4 Not specified whether singleton or multiple pregnancies 1 476 Risk Ratio (M-H, Random, 95% CI) 3.90 [1.11, 13.65]
32 Antenatal admissions (not prespecified) 2 893 Risk Ratio (M-H, Fixed, 95% CI) 0.72 [0.60, 0.88]
 32.1 Singleton pregnancy 2 893 Risk Ratio (M-H, Fixed, 95% CI) 0.72 [0.60, 0.88]
 32.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 32.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 32.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
33 Phototherapy for neonatal jaundice (not prespecified) 1 150 Risk Ratio (M-H, Fixed, 95% CI) 0.15 [0.01, 2.87]
 33.1 Singleton pregnancy 1 150 Risk Ratio (M-H, Fixed, 95% CI) 0.15 [0.01, 2.87]
 33.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 33.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 33.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
34 Abnormal neurological development at 9months (not pre-specified) 1 137 Risk Ratio (M-H, Fixed, 95% CI) 0.61 [0.26, 1.45]
 34.1 Singleton pregnancy 1 137 Risk Ratio (M-H, Fixed, 95% CI) 0.61 [0.26, 1.45]
 34.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 34.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 34.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
35 Hospitalisation for IUGR neonatal (not prespecified) 1 142 Risk Ratio (M-H, Fixed, 95% CI) 1.03 [0.75, 1.41]
 35.1 Singleton pregnancy 1 142 Risk Ratio (M-H, Fixed, 95% CI) 1.03 [0.75, 1.41]
 35.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 35.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 35.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
36 Fetal distress in labour (not prespecified) 1 289 Risk Ratio (M-H, Fixed, 95% CI) 0.35 [0.10, 1.22]
 36.1 Singleton pregnancy 1 289 Risk Ratio (M-H, Fixed, 95% CI) 0.35 [0.10, 1.22]
 36.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 36.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 36.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
37 Birth weight < 5 percentile (not prespecified) 1 289 Risk Ratio (M-H, Fixed, 95% CI) 1.16 [0.51, 2.64]
 37.1 Singleton pregnancy 1 289 Risk Ratio (M-H, Fixed, 95% CI) 1.16 [0.51, 2.64]
 37.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 37.3 Singleton plus multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 37.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
38 Periventricular leucomalacia (not prespecified) 1 545 Risk Ratio (M-H, Fixed, 95% CI) 0.33 [0.01, 8.00]
 38.1 Singleton pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 38.2 Multiple pregnancy 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
 38.3 Singleton plus multiple pregnancies 1 545 Risk Ratio (M-H, Fixed, 95% CI) 0.33 [0.01, 8.00]
 38.4 Not specified whether singleton or multiple pregnancies 0 0 Risk Ratio (M-H, Fixed, 95% CI) Not estimable
39 Antenatal hospital stay 1 426 Mean Difference (IV, Fixed, 95% CI) −0.60 [−2.39, 1.19]
 39.1 Singleton pregnancy 1 426 Mean Difference (IV, Fixed, 95% CI) −0.60 [−2.39, 1.19]
 39.2 Multiple pregnancy 0 0 Mean Difference (IV, Fixed, 95% CI) Not estimable
 39.3 Singleton plus multiple pregnancies 0 0 Mean Difference (IV, Fixed, 95% CI) Not estimable
 39.4 Not specified whether singleton or multiple pregnancies 0 0 Mean Difference (IV, Fixed, 95% CI) Not estimable