Table 1 Baseline characteristics

Maternal

Age at intake (years)^{a, b}

31.5 (22.5–38.1)

30.5 (20.1–38.3)

28.5 (19.0–37.7)

29.4 (20.0–37.5)

28.4 (18.4–39.9)

<0.001

Body mass index at intake (kg/m²)^{a, b}

23.1 (19.5–32.2)

23.2 (19.6–33.1)

23.7 (18.2–32.5)

22.8 (18.2–33.6)

24.8 (18.0–33.9)

NS

Education, n (%)

<0.001

Primary education

6 (1.8)

4 (8.5)

12 (9.6)

0 (0)

10 (17.9)

Secondary education

134 (40.1)

21 (44.7)

78 (62.4)

23 (56.1)

34 (60.7)

Higher education

193 (57.8)

22 (46.8)

33 (26.4)

17 (41.5)

11 (19.6)

Missing

1 (0.3)

0 (0.0)

2 (1.6)

1 (2.4)

1 (1.8)

Parity (%)

NS

0

220 (65.9)

34 (72.3)

82 (65.6)

28 (68.3)

35 (62.5)

≥1

114 (34.1)

13 (27.7)

43 (34.4)

13 (31.7)

21 (37.5)

Folic acid supplement use during pregnancy, n (%)

<0.001

Start preconception

188 (56.3)

18 (38.3)

29 (23.2)

11 (26.8)

15 (26.8)

Start postconception

84 (25.1)

19 (40.4)

36 (28.8)

13 (31.7)

13 (23.2)

No

25 (7.5)

7 (14.9)

33 (26.4)

10 (24.4)

14 (25)

Missing

37 (11.1)

3 (6.4)

27 (21.6)

7 (17.1)

14 (25)

Paternal smoking, n (%)

125 (37.4)

28 (59.6)

91 (72.8)

14 (34.1)

9 (16.1)

<0.001

<5 cigarettes per day

57 (17.1)

9 (19.1)

17 (13.6)

7 (17.1)

17 (30.4)

≥5 cigarettes per day

67 (20.1)

18 (38.3)

73 (58.4)

4 (9.8)

39 (69.6)

Newborns

Boys, n (%)

195 (58.4)

21 (44.7)

81 (64.8)

26 (63.4)

34 (60.7)

NS

Birth weight^{a, b}

3500 (2536–4383)

3410 (2154–4219)

3195 (2348–4081)

3175 (2663–4252)

3210 (2334–4150)

<0.001

Gestational age at birth^{a, b}

40.3 (37.6–42.0)

40.3 (36.5–41.9)

40.1 (37.1–42.5)

40.6 (37.0–42.9)

40.2 (36.9–42.3)

NS

IGF2DMR methylation (%)^a

54.0 (44.6–62.0)

52.2 (44.5–61.1)

51.6 (43.9–61.3)

52.0 (44.0–61.2)

51.1 (41.2–63.9)

0.033

H19 methylation (%)¹

30.0 (25.5–34.0)

30.8 (27.1–34.1)

30.2 (23.7–34.8)

29.8 (21.5–33.0)

30.2 (23.1–37.0)

NS