Table 1 Baseline characteristics stratified by fetal sex
Total | Females | Males | p value | |
|---|---|---|---|---|
n = 8556 | n = 4230 | n = 4326 | ||
Maternal age | 29.6 (5.3) | 29.6 (5.3) | 29.7 (5.3) | 0.49 |
Anthropometrics | ||||
Height (cm) | 167.5 (7.4) | 167.4 (7.5) | 167.6 (7.3) | 0.25 |
Weight (kg) | 66.3 (12.9) | 66.4 (12.9) | 66.1 (12.8) | 0.32 |
BMI (kg/m2) | 23.9 (19.4–33.8) | 24.0 (19.4–33.9) | 23.8 (19.3–33.7) | 0.12 |
Ethnicity | 0.44 | |||
Western | 4664 (57.5%) | 2316 (57.9%) | 2348 (57.1%) | |
Non-Western | 3447 (42.5%) | 1682 (42.1%) | 1765 (42.9%) | |
Educational level | 0.74 | |||
Low | 907 (11.6%) | 462 (12.0%) | 445 (11.3%) | |
Middle | 3627 (46.4%) | 1782 (46.2%) | 1845 (46.7%) | |
High | 3275 (41.9%) | 1611 (41.8%) | 1664 (42.1%) | |
Smoking habits | 0.004 | |||
No | 5452 (72.8%) | 2740 (73.9%) | 2712 (71.6%) | |
Yes-stopped | 642 (8.6%) | 330 (8.9%) | 312 (8.2%) | |
Yes-continued | 1399 (18.7%) | 636 (17.2%) | 763 (20.1%) | |
Folic acid use-yes (%) | 0.11 | |||
No | 1863 (29.3%) | 899 (28.5%) | 964 (30.2%) | |
Before 10 weeks | 1978 (31.1%) | 971 (30.7%) | 1007 (31.5%) | |
Preconception start | 2512 (39.5%) | 1289 (40.8%) | 1223 (38.3%) | |
Nulliparous (%) | 4718 (55.8%) | 2353 (56.4%) | 2365 (55.2%) | 0.89 |
Gestational age at sonography (wks) | ||||
First trimester | 12.5 (11.1–14.5) | 12.5 (11.1–14.4) | 12.5 (11.1–14.6) | 0.04 |
Second trimester | 20.5 (18.9–22.9) | 20.4 (18.8–22.8) | 20.6 (18.9–23.0) | <0.001 |
Third trimester | 30.3 (28.7–32.4) | 30.3 (28.6–32.4) | 30.4 (28.9–32.4) | <0.001 |
Gestational age at birth (wks) | 40.1 (36.9–42.0) | 40.1 (36.9–42.0) | 40.1 (36.7–42.1) | 0.001 |