Table 1.

Maternal thyroid function tests during the course of pregnancy

	34-wk gestation	28-wk gestation	20-wk gestation
TSH	0.21 (0.1-4.0 mIU/L)	0.42 (0.1-4.0 mIU/L)	0.51 (0.1-4.0 mIU/L)
Free T4	16.8 (12-22 pmol/L) 1.31 (0.93-1.71 ng/dL)	15.4 (12-22 pmol/L) 1.2 (0.93-1.71 ng/dL)	16.8 (12-22 pmol/L) 1.31 (0.93-1.71 ng/dL)
Free T3			4.9 (3.1-6.8 pmol/L) 3.18 (2.0-4.42 pg/mL)
TRAb			<0.8 (0-1.8 IU/L)

Système International (SI) unit ÷ conversion factor (CF) = conventional unit (free T4 CF 12.87, free T3 CF 1.54).

Abbreviations: T3, 3,5,3′-triiodothyronine; T4, thyroxine; TRAb, thyrotropin receptor antibody; TSH, thyrotropin.