(a)
| Variable | Cases Mean (SD) | Control Mean (SD) | All Mean (SD) | P value |
|---|---|---|---|---|
| Age | 17.4 (6.0) | 18.7 (3.4) | 18.1 (5.0) | 0.183 |
| Parity | 0.8 (1.4) | 0.9 (1.1) | 0.7 (1.3) | 0.585 |
| Gestational age (weeks) | 39.7 (1.2) | 38.2 (1.3) | 39.1 (1.3) | 0.42 |
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