. 2021 Aug 17;10(9):1125–1133. doi: 10.1530/EC-21-0376

Table 3.

The association between maternal BMI and smoking status in pregnancy and different measures of maternal thyroid thyroxine (T4) and triiodothyronine (T3) in the early pregnancy.

	n	Free T4 index (nmol/L)^a,b			Total T4 (nmol/L)^a			Total T3 (nmol/L)^a			Free T3 (pmol/L)^a
	n	Mean^c	aβ^d	95% CI	Mean^c	aβ^d	95% CI	Mean^c	aβ^d	95% CI	Mean^c	aβ^d	95% CI
BMI (kg/m²)^e
<18.5	216	118	1.03	1.00–1.05	128	1.01	0.981–1.03	2.24	0.986	0.976–0.997	5.06	0.997	0.980–1.01
18.5–24.9	3096	115	Ref.		127	Ref.		2.27	Ref.		5.02	Ref.
25.0–29.9	1350	112	0.977	0.965–0.988	127	1.01	0.997–1.02	2.41	1.03	1.02–1.03	5.13	1.02	1.01–1.03
30.0–34.9	571	111	0.970	0.954–0.987	129	1.02	1.00–1.04	2.53	1.05	1.04–1.05	5.22	1.03	1.02–1.05
≥35.0	296	109	0.960	0.939–0.982	127	1.01	0.990–1.04	2.59	1.06	1.05–1.07	5.28	1.05	1.03–1.06
Smoking^f
Non-smoking	4958	114	Ref.		128	Ref.		2.33	Ref.		5.05	Ref.
Smoking	571	111	0.975	0.960–0.991	124	0.969	0.953–0.985	2.53	1.03	1.02–1.04	5.33	1.04	1.03–1.05

^aMethod A (Cobas 8000, Roche Diagnostics). ^bCalculated as total T4 divided by T-uptake. ^cGeometric mean. ^dAdjusted model included maternal BMI, smoking, age, parity, gestational week of blood sampling, origin, and diabetes. ^eMaternal pre-pregnancy BMI. ^fMaternal smoking in the pregnancy.

aβ, adjusted exponentiated beta coefficient.