Risk factors for study outcomes, multivariable estimates (GA at enrolment ≤20 weeks)
| Characteristics | Study outcomes | ||||
| Caesarean sections n=11 628, 24% RR (95% CI)† | Pregnancy-related maternal complications n=6762, 14% RR (95% CI)† | Stillbirths n=1104, 2.3% RR (95% CI)† | Neonatal deaths (within 28 days of birth) n=963, 2.0% RR (95% CI)† | Low birth weight (<2500 g) n=8378, 18% RR (95% CI)† | |
| Mother’s age (years) | |||||
| <20 | 0.83†* (0.73 to 0.95) | 0.83* (0.72 to to 0.97) | 0.73 (0.47 to 1.12) | 1.23 (0.87 to 1.75) | 1 (0.88 to –1.15) |
| 20–29 | Ref | Ref | Ref | Ref | Ref |
| >29 | 1.56** (1.44 to 1.68) | 1.37** (1.22 to 1.53) | 1.45* (1.13–1.86) | 1.37* (1.03 to 1.80) | 1.27** (1.15 to 1.40) |
| Mother’s education (grades) | |||||
| Primary or less (≤4) | 0.50** (0.46 to 0.54) | 0.76** (0.70 to 0.83) | 1.68** (1.39 to 2.04) | 1.53** (1.24 to 1.87) | 1.17** (1.08 to 1.25) |
| Secondary (5–10) | 0.70** (0.67 to 0.73) | 0.90** (0.85 to 0.94) | 1.40** (1.21 to 1.61) | 1.30** (1.12 to 1.52) | 1.15** (1.09 to 1.21) |
| University (>10) | Ref | Ref | Ref | Ref | Ref |
| Parity | |||||
| Nulliparous | 1.33** (1.28 to 1.39) | 2.00** (1.86 to 2.15) | 1.32** (1.17 to 1.50) | 1.57** (1.38 to 1.80) | 1.38** (1.31 to 1.44) |
| 1–2 | Ref | Ref | Ref | Ref | Ref |
| >2 | 0.49** (0.40 to 0.60) | 0.80* (0.63 to 1.00) | 1.50* (1.06 to 2.13) | 1.62* (1.10 to 2.37) | 0.99 (0.85 to 1.17) |
| Anaemia (g/dL) | |||||
| Severe/moderate (<10) | 0.89** (0.84 to 0.95) | 0.90* (0.83 to 0.98) | 1.16 (0.92 to 1.46) | 1.37* (1.06 to 1.77) | 1.24** (1.14 to 1.35) |
| Mild (10–11) | 0.91* (0.86 to 0.97) | 0.92* (0.85 to 0.99) | 1.12 (0.88 to 1.41) | 1.16 (0.90 to 1.50) | 1.09 (1.00 to 1.18) |
| Normal (≥11) | Ref | Ref | Ref | Ref | Ref |
| Body mass index (kg/m2) | |||||
| Underweight (<18.5) | 0.81** (0.77 to to 0.84) | 0.83** (0.79 to 0.88) | 1.08 (0.96 to 1.22) | 1.09 (0.96 to 1.24) | 1.18** (1.13 to 1.23) |
| Normal (18.5–24.9) | Ref | Ref | Ref | Ref | Ref |
| Overweight or obese (≥25) | 1.64** (1.51 to 1.78) | 1.44** (1.28 to 1.61) | 1.19 (0.84 to 1.67) | 1.25 (0.87 to 1.79) | 0.91 (0.79 to 1.04) |
*P<0.05, **p<0.001.
†Obtained by multivariable GEE regression models for each outcome, separately.
GA, gestational age; GEE, generalised estimating equations.