Table 1.

Characteristics of the study participants, i.e. 307 mother-infant pairs recruited in 1996-1999

Characteristic	N	Median (Range)
Maternal age (years)	307	28 (18–41)
Maternal pre-pregnancy BMI (kg/m2)	307	23 (18–44)
Maternal weight gain during pregnancy (%)a	304	22 (3.9–46)
Gestational length (days)b	138	280 (249–300)
Birth weight of the child (g)b	150	3510 (2430–5000)
Age of infant at 3-weeks-sampling (days)b	148	24 (17–38)
Weight of the infant at 3 monthsc	109	6180 (4350–8600)
Age of infant at 3-months-sampling (days)c	115	91 (75–123)
Maternal serum TH concentrations, early pregnancy
TSH (mIU/L)	220	1.3 (0.002–7.5)
Total T3 (nmol/L)	219	2.4 (0.57–3.7)
Free T4 (pmol/L)	220	11 (7.8–20)
Maternal serum TH concentrations, late pregnancy
TSH (mIU/L)	281	1.4 (0.06–6.7)
Total T3 (nmol/L)	281	2.5 (1.1–3.8)
Free T4 (pmol/L)	281	8.3 (5.7–13)
anti-TPOd (kIU/L)	260	8.6 (5.5–134)
Infant serum TH concentrations, 3 weeks of age
TSH (mIU/L)	148	2.4 (0.54–6.4)
Total T3 (nmol/L)	145	2.8 (1.4–4.2)
Free T4 (pmol/L)	150	17 (12–23)
Infant serum TH concentrations, 3 months of age
TSH (mIU/L)	115	1.8 (0.77–4.8)
Total T3 (nmol/L)	115	3.0 (1.7–4.2)
Free T4 (pmol/L)	114	15 (10–22)
	N	%
Country of birth
Nordic country	291	95
Non-Nordic country	16	5
Years of education
≤4 years of high school	144	49
1–3 years of higher education	72	24
>3 years of higher education	79	27
Smoking habits during pregnancy (smoker/non-smoker)	58/194	19/81
Alcohol during pregnancy (no/yes)	254/52	83/17
Mode of delivery (vaginal/caesarean)b	120/18	87/13
Sex of the child (male/female)b	83/67	55/45

^a(weight gain during pregnancy/weight before pregnancy)*100

^bAmong 150 infants with analysed THs in serum at 3 weeks of age

^cAmong 115 infants with analysed THs in serum at 3 months

^dThyroid peroxidase antibodies