Table 1.

Characteristics of the study participants

Characteristic	All women (N = 1858)a
Maternal age (years)	30 (27–34)
Pregestational BMI (kg/m2)	20.03 (18.80–21.51)
TSH (mIU/L), n (%)	1.07 (0.58–1.68)
< 0.1	153 (8.2)
≥0.1 and < 2.5	1532 (82.5)
≥2.5 and < 4.0	142 (7.6)
≥4.0	31 (1.7)
FT4 (pmol/L)	16.52 (14.46–18.73)

^aMedian (interquartile range) or n (%)

BMI body mass index, TSH thyroid-stimulating hormone, FT4 free thyroxine 4