Table 3.
Association between interpregnancy BMI change status and outcomes of second pregnancy, by weight status at 12-week gestation in the first pregnancy.
| Outcomes of second pregnancy | BMI < 23 kg/m2 | BMI ≥ 23 kg/m2 | P-interaction | ||||
|---|---|---|---|---|---|---|---|
| Loss | Moderate gain | Excess gain | Loss | Moderate gain | Excess gain | ||
| (> 1 kg/m2) | (1 to < 3 kg/m2) | (≥ 3 kg/m2) | (> 1 kg/m2) | (1 to < 3 kg/m2) | (≥ 3 kg/m2) | ||
| RR (95% CI) | RR (95% CI) | RR (95% CI) | RR (95% CI) | RR (95% CI) | RR (95% CI) | ||
| Offspring birth weight | |||||||
| Low < 2.5 kg (vs. Normal 2.5 to < 4 kg) | 1.22 (0.79, 1.90) | 0.84 (0.63, 1.11) | 1.07 (0.72, 1.59) | 1.64 (1.09, 2.47) | 1.43 (0.99, 2.07) | 1.06 (0.66 2.71) | 0.076 |
| High ≥ 4 kg (vs. Normal 2.5 to < 4 kg) | 0.52 (0.07, 4.04) | 1.30 (0.56, 3.02) | 3.00 (1.17, 7.68) | 0.93 (0.46, 1.86) | 1.01 (0.58, 1.76) | 1.34 (0.74, 2.43) | 0.428 |
| Offspring birth size | |||||||
| SGA < 10 percentile (vs. AGA 10–90 percentile) | 0.96 (0.63, 1.45) | 0.84 (0.67, 1.06) | 0.88 (0.62, 1.25) | 1.54 (1.02, 2.34) | 1.29 (0.91, 1.83) | 0.90 (0.58, 1.42) | 0.078 |
| LGA > 90 percentile (vs. AGA 10–90 percentile) | 0.73 (0.49, 1.09) | 1.16 (0.96, 1.40) | 1.67 (1.30, 2.15) | 0.88 (0.71, 1.10) | 1.13 (0.97, 1.31) | 1.23 (1.03, 1.46) | 0.092 |
| Preterm delivery < 37 weeks | |||||||
| Yes (vs. No) | 1.03 (0.65, 1.65) | 0.82 (0.60, 1.12) | 1.24 (0.81, 1.88) | 1.09 (0.74, 1.61) | 1.13 (0.83, 1.53) | 1.02 (0.71, 1.48) | 0.327 |
| Gestational diabetes | |||||||
| Yes (vs. No) | 1.22 (0.76, 1.95) | 1.11 (0.83, 1.48) | 1.77 (1.20, 2.61) | 0.99 (0.74, 1.31) | 1.27 (1.03, 1.58) | 1.50 (1.20, 1.88) | 0.541 |
| Mode of delivery | |||||||
| Elective caesarean (vs. vaginal delivery) | 1.10 (0.89, 1.36) | 1.09 (0.97, 1.22) | 1.09 (0.92, 1.28) | 0.97 (0.84, 1.13) | 0.97 (0.88, 1.07) | 1.02 (0.91 1.16) | 0.348 |
| Emergency caesarean (vs. vaginal delivery) | 1.34 (0.96, 1.88) | 1.31 (1.07, 1.59) | 1.35 (1.04, 1.77) | 0.98 (0.82, 1.17) | 1.06 (0.91, 1.24) | 1.05 (0.89, 1.23) | 0.133 |
Risk ratios are adjusted for maternal age and BMI at 12-week gestation in the first pregnancy, ethnicity, interpregnancy interval and respective pregnancy outcomes in the first pregnancy. BMI stable (− 1 to < 1 kg/m2) serves as the reference group. BMI, body mass index; RR, risk ratio; CI, confidence interval; AGA, appropriate for gestational age; SGA, small-for-gestational-age; LGA, large-for-gestational-age.