Table 1.

Baseline characteristics of Lifelines controls and Eurocat cases. [CHD=congenital heart defects.]

	Controls (N=5602)		CHD (N=1174)		P-value
	N	%	N	%
Child sex					<0.01
Male	2731	48.8	632	53.8
Female	2871	51.2	542	46.2
Birth year					0.12
1997–2000	1240	22.1	266	22.8
2001–2004	1660	29.6	310	26.1
2005–2008	1293	23.1	298	25.5
2009–2013	1409	25.2	300	25.6
Maternal age at delivery					<0.01
15–19 a	3	0.1	1	0.1
20–24	191	3.6	100	8.7
25–29	1492	28.2	362	31.6
30–34	2470	46.7	479	16.2
35–39	1058	20.0	194	16.9
≥40	73	1.4	11	1.0
Unknown	315		27
Education level					<0.01
Low	649	12.3	162	14.0
Middle	2396	45.4	561	48.6
High	2236	42.3	432	37.4
Unknown	321		19
Body mass index (kg/m2) b					<0.01
<18.5	56	1.0	31	2.7
18.5–24.9	2871	53.6	738	64.6
25.0–29.9	1610	30.1	269	23.5
≥30	818	15.3	105	9.2
Unknown	247		32
Smoking during first trimester					<0.01
No	5036	90.2	903	77.2
Yes	549	9.8	267	22.8
Unknown	17		4
Alcohol during first trimester					<0.01
No	5045	90.3	873	74.6
Yes	544	9.7	297	25.4
Unknown	13		4
Folic acid use					<0.01
No	847	16.5	290	24.9
Yes	4272	83.5	873	75.1
Unknown	483		11
Fertility problems					<0.01
No	5230	93.9	971	83.6
Yes	339	6.1	190	16.4
Unknown	33		13

^aLifelines includes participants from 18 years old.

^bBody mass index of Eurocat cases is based on self-reported height and weight. Height and weight of Lifelines participants is measured at the baseline visit to the study clinic.