Table 6.

Characteristics of mothers and sons at baseline (pregnancy week 30) and follow-up according to the level of participation.

Characteristics	Participating in physical examination, n=176	Filling in questionaire only, n=157	Not in follow-up, n=143	P value
Maternal
ΣPCBs (pmol/ml), median (p25–p75)	10.1 (7.3–12.9)	10.4 (7.6–13.0)	9.0 (6.6–12.2)	0.12 a
ΣDioxin-like-PCBs (pmol/ml), median (p25–p75)	0.8 (0.6–1.1)	0.8 (0.6–1.1)	0.8 (0.6–1.0)	0.11 a
p,p′-DDE (pmol/ml), median (p25–p75)	8.2 (5.2–12.4)	7.3 (4.9–11.2)	8.0 (5.1–11.9)	0.48 a
Maternal age (years), mean (s.d.)	29.6 (4.4)	29.0 (4.2)	28.3 (4.5)	0.03 b
Prepregnancy BMI (kg/m2), median (p25–p75)	21.0 (19.8–22.3)	20.7 (19.5–22.7)	21.2 (19.1–23.1)	0.77 a
Nulliparous, n (%)	112 (64)	96 (61)	83 (58)	0.60 c
Smoking during pregnancy, n (%)	55 (33)	53 (37)	63 (47)	0.03 c
High social class, n (%)	96 (60)	87 (64)	77 (61)	0.78 c
Blood total lipid level (g/l), median (p25–p75)	8.6 (7.7–9.6)	8.8 (7.9–10.0)	8.7 (7.9–9.6)	0.33 a
Alcohol during pregnancy (g/day), median (p25–p75)	2.0 (0.4–4.6)	1.5 (0–4.4)	1.5 (0–3.5)	0.53 a
Male offspring follow-up
BMI (kg/m2), median (p25–p75) d	22.2 (20.5–24.1)	22.4 (20.7–24.4)	–	0.50 e
Current/occasional smoker, n (%)	83 (50)	66 (43)	–	0.24 c
History of reproductive tract disease, n (%)	23 (14)	11 (7)	–	0.06 c

^aKruskal–Wallis test.

^bOne-way ANOVA test.

^c χ ²-test.

^dBMI is calculated from anthropometric measures based on self-reported values.

^eWilcoxon rank-sum test.