Table 4.

The association between maternal BMI and smoking status in pregnancy and different measures of maternal triiodothyronine (T3)/thyroxine (T4) ratio stratified by week of pregnancy.

	n	Free T3/free T4 ratioa			Total T3/total T4 ratioa
		Meanb	aβc	95% CI	Meanb	aβc	95% CI
BMI (kg/m2)d
Week 4–8
18.5–24.9	284	0.304	Ref.		0.018	Ref.
≥25.0	242	0.324	1.07	1.04–1.09	0.020	1.07	1.04–1.09
Week 9–11
18.5–24.9	2492	0.298	Ref.		0.018	Ref.
≥25.0	1756	0.317	1.06	1.05–1.07	0.019	1.07	1.06–1.08
Week 12–14
18.5–24.9	320	0.298	Ref.		0.018	Ref.
≥25.0	219	0.321	1.07	1.04–1.09	0.020	1.08	1.05–1.11
Smokinge
Week 4–8
Non-smoking	472	0.301	Ref.		0.019	Ref.
Smoking	73	0.329	1.05	1.02–1.09	0.021	1.09	1.05–1.13
Week 9–11
Non-smoking	3991	0.302	Ref.		0.018	Ref.
Smoking	431	0.332	1.08	1.07–1.10	0.020	1.11	1.09–1.13
Week 12–14
Non-smoking	495	0.304	Ref.		0.018	Ref.
Smoking	67	0.322	1.03	0.995–1.07	0.020	1.05	1.01–1.10

^aMethod A (Cobas 8000, Roche Diagnostics). ^bGeometric mean. ^cAdjusted model included maternal BMI, smoking, age, parity, origin, and diabetes. ^dMaternal pre-pregnancy BMI. ^eMaternal smoking in the pregnancy.

aβ, adjusted exponentiated beta coefficient.