Table 3.
Pregnancy and baby secondary outcomes
| Intervention (n=227 860) | Control (n=157 692) | Adjusted OR (95% CI) | p value | Absolute effect (95% CI) per 10 000 pregnancies or per 10 000 babies* | |
|---|---|---|---|---|---|
| Preterm pregnancy | 17 376 (7·7%) | 11 228 (7·3%) | 1·05 (1·00–1·10) | 0·050 | 34 more (0–68 more) |
| Caesarean section | 64 572 (28·3%) | 40 231 (25·5%) | 1·09 (1·06–1·12) | <0·0001 | 162 more (105–218 more) |
| Induction at ≥39 weeks' gestation | 57 815 (39·8%) | 33 317 (33·6%) | 1·08 (1·04–1·11) | <0·0001 | 165 more (88–245 more) |
| Induction of labour | 83 499 (40·7%) | 49 952 (35·8%) | 1·05 (1·02,1·08) | 0·0015 | 108 more (41–177 more) |
| Elective delivery | 111 837 (54·6%) | 67 227 (48·2%) | 1·04 (1·01–1·07) | 0·0123 | 91 more (20–160 more) |
| Elective delivery at ≥39 weeks' gestation | 76 247 (52·4%) | 44 838 (45·2%) | 1·05 (1·02–1·09) | 0·0022 | 128 more (47–212 more) |
| Spontaneous vaginal delivery | 130 658 (57·4%) | 94 337 (59·8%) | 0·90 (0·88–0·92) | <0·0001 | 256 fewer (319–194 fewer) |
| Admitted to neonatal unit | 19 237 (10·1%) | 13 029 (10·1%) | 1·02 (0·97–1·07) | 0·504 | 14 more (28 fewer to 59 more)* |
| Admitted to neonatal unit for >48 h | 12 676 (6·7%) | 8041 (6·2%) | 1·12 (1·06–1·18) | 0·0001 | 68 more (32 to 105 more)* |
| Admitted to neonatal unit at ≥37 weeks' gestation | 10 384 (6·0%) | 7497 (6.5%) | 0·95 (0·89–1·01) | 0·091 | 32 fewer (66 fewer to 5 more)* |
| Small for gestational age (≤10th centile) delivered ≥40 weeks' gestation | 3461 (1·5%) | 3081 (2·0%) | 0·86 (0·78–0·95) | 0·0009 | 27 fewer (42–10 fewer)* |
| Preterm baby | 19 815 (8·6%) | 12 738 (8·1%) | 1·05 (1·00–1·10) | 0·061 | 34 more (1 fewer to 72 more)* |
Data are n (%). ORs are adjusted for maternal age, number of babies in the pregnancy and study time period and cluster. Data are missing for preterm pregnancy (4307 [1·1%]), caesarean section (95 [0·02%]), induction at ≥39 weeks (140 930 [36·6%]), induction of labour (41 183 [10·7%]); elective delivery (41 239 [10·7%]), elective delivery at ≥39 weeks' gestation 140 945 [36·6%]), spontaneous vaginal delivery (95 [0·02%]), admitted to neonatal unit (72 405 [18·5%]), admitted to neonatal unit for >48h (72 405 [18·5%]), admitted to neonatal unit at ≥37 weeks' gestation (103 029 [26·3%]), small for gestational age (≤10th centile) delivered ≥40 weeks' gestation (6963 [1·8%]), and preterm baby 4372 [1·1%]). OR=odds ratio.
Absolute effect sizes are per 10 000 babies for outcomes of neonatal unit admission, born small for gestational age, or preterm baby.