Table 1 Descriptive statistics for mothers in the study

Maternal age at measurement

27.82 (24.99, 30.79)

Days pregnant at measurement

207 (160, 288)

Current smoker?

17 (5.7%)

Grade completed

11.2 (2.0, 22.0)

SES z-score

0.06 (− 3.32, 5.10)

Pre-pregnancy BMI z-score

0.02 (− 1.89, 3.90)

Pregnancy number

1

41 (14%)

2

87 (29%)

3

67 (23%)

4

52 (18%)

5

25 (8.4%)

6 + 

23 (8.1%)