Table 1 Baseline Characteristics for total cohort (n = 308)

Age (years)^a

31(5)

Booking BMI (kg/m²)^b

24.4 (22.0, 28.3)

Gestation (weeks)^b

37.0 (36.1, 37.6)

Primiparous

128 (42%)

Smoking

31 (10%)

Caucasian

295 (96%)

TSH (mIU/l)^b

1.9 (1.4, 2.6)

Free T4 (pmol/l)^a

12.0 (1.6)

TPO-Ab positive

16/305 (5%)

Urinary Iodine (μg/l)^b

88 (55, 157)

Urinary Perchlorate (μg/l)^b

2.1 (1.4,3.8)

Urinary Thiocyanate (μg/l)^b

436 (302,683)