Table 1.

Socio-demographic data for the study population

	Index group		Control group
	N	%	N	%	P-value
					Index vs. Control
Age (mean/SD)**	30.6/6.09		30.3/5.16		0.602
Marital status*					0.989
Married/Cohabiting	133	92.4	150	93.2
Single	11	5.6	11	6.8
Sick leave at registration*					0.014
Yes	9	7.0	2	1.3
No	120	93.0	156	98.7
Socioeconomic group*					0.132
Higher education	41	33.6	63	40.1
Lower education	47	38.5	52	33.1
Unemployed/parental leave	21	17.2	16	10.2
Student	13	10.7	26	16.6
BMI in the beginning of pregnancy*					0.540
−24.9	60	45.8	80	50.6
25–29.9	46	35.1	55	34.8
30-	25	19.1	23	14.5
Tobacco use*					0.007
Yes	30	22.6	17	10.7
No	103	77.4	142	89.3
Parity*					0.085
0	78	49.1	84	50.3
1	43	27.0	58	34.7
2 or more	38	23.9	25	15.0

*P-value for Students t-test

**P-value for Pearson’s x ²-test