Summary of data analysis on outcomes of interest
| Outcome | Studies (N) | Participants | Pooled RR (95% CI) | I2 (%) | p Value |
|---|---|---|---|---|---|
| Primary outcomes | |||||
| Antenatal hospitalisation | 4 | 5187 | 1.02 (0.93 to 1.11) | 15 | 0.72 |
| Breastfeeding initiation | 3 | 5067 | 1.01 (0.95 to 1.08) | 56 | 0.75 |
| Caesarean birth | 11 | 15 919 | 0.92 (0.85 to 1.00) | 2 | 0.04 |
| Induction of labour | 9 | 14 924 | 0.90 (0.81 to 0.99) | 59 | 0.03 |
| Instrumental vaginal delivery (forceps/vacuum) | 9 | 14 924 | 0.93 (0.86 to 1.01) | 0 | 0.08 |
| Preterm birth (<37 weeks)—adjusted for cluster design effect (ICC 0.002) | 15 | 0.84 (0.74 to 0.96) | 49 | 0.01 | |
| 14 | 0.84 (0.73 to 0.97) | |||
| Cluster randomisation | 1 | 0.83 (0.59 to 1.16) | |||
| Preterm birth (<37 weeks)—sensitivity analysis (ICC 0.0041) | 15 | 0.83 (0.72 to 0.95) | 51 | 0.007 | |
| Individualised randomised trials | 14 | 0.84 (0.73 to 0.97) | |||
| Cluster randomisation | 1 | 0.69 (0.47 to 1.02) | |||
| Preterm birth (<37 weeks)—all studies, unadjusted data | 15 | 22 437 | 0.86 (0.76 to 0.97) | 42 | 0.01 |
| Individualised randomised trials | 14 | 19 783 | 0.86 (0.75 to 0.98) | ||
| Cluster randomisation | 1 | 2654 | 0.81 (0.62 to 1.06) | ||
| Spontaneous vaginal birth (as defined by trial authors) | 9 | 14 924 | 1.05 (1.01 to 1.10) | 65 | 0.01 |
| Secondary outcomes | |||||
| 5-min Apgar score ≤7 | 9 | 10 779 | 0.86 (0.68 to 1.09) | 0 | 0.21 |
| Admission to special care unit/NICU | 11 | 15 225 | 0.94 (0.84 to 1.05) | 15 | 0.25 |
| Fetal loss/ neonatal death before 24 weeks | 9 | 14 968 | 0.81 (0.65 to 1.02) | 0 | 0.07 |
| Fetal loss/ neonatal death equal to/after 24 weeks | 8 | 13 294 | 0.97 (0.60 to 1.58) | 0 | 0.91 |
| Low birthweight (<2500 g)—adjusted for cluster design effect (ICC 0.0003) | 10 | 0.83 (0.61 to 1.13) | 85 | 0.23 | |
| Individualised randomised trials | 9 | 0.77 (0.55 to 1.09) | |||
| Cluster randomisation | 1 | 1.38 (1.00 to 1.92) | |||
| Low birthweight (<2500 g)—sensitivity analysis (ICC 0.0016) | 10 | 0.82 (0.60 to 1.12) | 78 | 0.22 | |
| Individualised randomised trials | 9 | 0.77 (0.55 to 1.09) | |||
| Cluster randomisation | 1 | 1.36 (0.92 to 2.00) | |||
| Low birthweight (<2500 g)—all studies, unadjusted data | 10 | 17 992 | 0.98 (0.89 to 1.09) | 0 | 0.76 |
| Individualised randomised trials | 9 | 15 338 | 0.99 (0.89 to 1.11) | ||
| Cluster randomisation | 1 | 2654 | 0.91 (0.67 to 1.25) | ||
| Mean length of neonatal hospital stay (days) | MD (95% CI) | ||||
| 3 | 2027 | −2.11 (−4.64 to 0.41) | 69 | 0.10 | |
ICC, intracluster correlation coefficient; MD, mean difference; NICU, neonatal intensive care unit; RR, risk ratios.