Table 4.
Odds of preterm birth, early term birth, and small for gestational age by interpregnancy interval in a propensity score-matched sample (n = 83,788)
| Birth outcome | Interpregnancy interval subgroups n (%) OR (95% CI) |
|||||
|---|---|---|---|---|---|---|
| < 6 months n = 14,748 | 18–23 months n = 14,748 | 6–11 months n = 29,668 | 18–23 months n = 29,668 | 12–17 months n = 36,108 | 18–23 months n = 36,108 | |
| < 32 weeks GA | 131 (0.9) | 58 (0.4) | 155 (0.5) | 102 (0.3) | 142 (0.4) | 120 (0.3) |
| 2.50 (1.83, 3.41) | Ref | 1.58 (1.23, 2.03) | Ref | 1.19 (0.94, 1.52) | Ref | |
| 32–36 weeks GA | 1055 (7.2) | 637 (4.3) | 1427 (4.8) | 1247 (4.2) | 1455 (4.0) | 1474 (4.1) |
| 1.83 (1.66, 2.03) | Ref | 1.19 (1.10, 1.29) | Ref | 1.00 (0.92, 1.07) | Ref | |
| < 37 weeks GA (any preterm) | 1186 (8.0) | 695 (4.7) | 1582 (5.3) | 1349 (4.6) | 1597 (4.4) | 1594 (4.4) |
| 1.89 (1.71, 2.08) | Ref | 1.22 (1.13, 1.31) | Ref | 1.01 (0.94, 1.09) | Ref | |
| 37–38 weeks GA (early term) | 4401 (29.8) | 3907 (26.5) | 8216 (27.7) | 7691 (25.9) | 9359 (25.9) | 9156 (25.4) |
| 1.25 (1.19, 1.31) | Ref | 1.11 (1.07, 1.15) | Ref | 1.03 (1.00, 1.07) | Ref | |
| SGA | 1,024 (6.9) | 938 (6.4) | 1,753 (5.9) | 1,763 (5.9) | 1,949 (5.4) | 2,069 (5.7) |
| 1.10 (1.00, 1.20)a | Ref | 0.99 (0.93, 1.06) | Ref | 0.94 (0.88, 1.00) | Ref | |
GA gestational age at birth, SGA small for gestational age, OR odds ratio
ap < 0.05