Table 3.
Maternal characteristics and foetal sex.
| % (n) or mean [s.d.] | ||||
|---|---|---|---|---|
| male foetus (n=372) | female foetus (n=368) | test statistica | p-value | |
| current smokerb | 39.0 (145) | 42.4 (156) | 0.89 | 0.35 |
| cigarettes yesterday (n) | ||||
| 0 | 73.9 (275) | 69.8 (257) | 1.72 | 0.27 |
| 1–8 | 14.8 (55) | 17.4 (64) | ||
| 9–16 | 8.6 (32) | 9.2 (34) | ||
| 17 or more | 2.7 (10) | 3.5 (13) | ||
| folic acid used prior to conception | 34.4 (128) | 34.2 (126) | 0.002 | 0.96 |
| education | ||||
| <O level | 23.1 (86) | 19.6 (72) | 1.40 | 0.50 |
| O level | 51.1 (190) | 53.5 (197) | ||
| >O level | 25.8 (96) | 26.9 (99) | ||
| age (years) | 25.8 [5.0] | 25.8 [4.9] | 0.01 | 0.92 |
| weight prior to conception (kg)c | 62.8 [11.7] | 62.6 [15.0] | 0.06 | 0.80 |
| weight at booking (kg)d | 67.2 [12.5] | 66.2 [12.3] | 1.16 | 0.28 |
| height (cm) | 164.3 [6.5] | 164.3 [6.6] | 0.01 | 0.91 |
| body mass index prior to conception (kg m−2)c | 23.2 [4.0] | 23.2 [5.3] | 0.06 | 0.81 |
| body mass index at first antenatal clinic (kg m−2)d | 24.9 [4.3] | 24.5 [4.3] | 1.18 | 0.28 |
a
Wald Χ2-test for continuous and categorical predictors in logistic models.
b
Defined by self-report or by a serum cotinine concentration greater than 14 ng ml−1 in self-reported ‘non-smokers’.
c
Data missing from medical records for 18 (4.8%) mothers of boys and 11 (3.0%) mothers of girls.
d
Data missing from medical records for 9 (2.4%) mothers of boys and 11 (3.0%) mothers of girls.