Table 1.
Characteristics of the 1 742 831 singleton white European pregnancies without congenital anomalies in the Netherlands, 1999‐2010
| Male infants | Female infants | P value | |
|---|---|---|---|
| (n = 895 272) | (n = 847 559) | ||
| Maternal characteristics | |||
| Maternal age, years (mean), (SD) | 30.7 (4.6) | 30.7 (4.7) | 0.24 |
| Nulliparous, n (%) | 426 995 (47.7) | 403 106 (47.6) | 0.08 |
| Low socioeconomic status, n (%) | 172 737 (19.3) | 163 006 (19.2) | 0.30 |
| Pregnancy and delivery characteristics | |||
| Conception IVF/ICSI, n (%) | 24 856 (2.8) | 23 375 (2.8) | 0.46 |
| Hypertensive disordersa, n (%) | 83 170 (9.3) | 76 100 (9.0) | <0.0001 |
| Induction of labor, n (%) | 191 330 (21.4) | 182 001 (21.5) | 0.10 |
| Mode of delivery | |||
| Spontaneous vaginal delivery, n (%) | 654 129 (73.1) | 647 524 (76.4) | <0.0001 |
| Instrumental vaginal delivery, n (%) | 109 448 (12.2) | 84 552 (10.0) | |
| Elective cesarean, n (%) | 55 269 (6.2) | 55 556 (6.6) | |
| Emergency cesarean, n (%) | 76 426 (8.5) | 59 957 (7.1) | |
| Neonatal characteristics | |||
| Gestational age at delivery (wk), median (IQR) | 39 (38‐40) | 40 (39‐40) | <0.0001 |
| Delivery <32 wk GA, (%) | 8110 (0.9) | 6438 (0.8) | <0.0001 |
| Delivery <37 wk GA, (%) | 57 353 (6.4) | 45 980 (5.4) | <0.0001 |
| Birthweight (g), mean (SD) | 3525 (597) | 3401 (564) | <0.0001 |
| Birthweight <p10 (SGA) | 79 442 (8.9) | 75 691 (8.9) | |
| Birthweight p10‐p90 (normal weight) | 719 424 (80.4) | 677 826 (80.0) | |
| Birthweight ≥p90 (LGA) | 96 406 (10.8) | 94 042 (11.1) | |
Abbreviation: SD, standard deviation.
a
Preexisting hypertension, pregnancy‐induced hypertension, preeclampsia.