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

Table 2.

The association between maternal BMI and smoking status in pregnancy and levels of maternal thyroid-stimulating hormone (TSH) and free thyroxine (T4) in the early pregnancy assessed using different biochemical methods.

	n	TSH (mIU/L)^a			TSH (mIU/L)^b			Free T4 (pmol/L)^a			Free T4 (pmol/L)^b
	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	0.887	0.911	0.801–1.04	0.778	0.910	0.800–1.04	17.2	1.02	1.01–1.04	16.7	1.02	1.01–1.04
18.5–24.9	3096	0.985	Ref.		0.861	Ref.		16.8	Ref.		16.3	Ref.
25.0–29.9	1350	1.05	1.07	1.01–1.13	0.917	1.07	1.01–1.14	16.4	0.974	0.965–0.982	16.2	0.988	0.980–0.996
30.0–34.9	571	1.17	1.19	1.10–1.30	1.03	1.20	1.10–1.30	16.2	0.963	0.952–0.975	16.0	0.981	0.970–0.993
≥35.0	296	1.31	1.34	1.20–1.50	1.16	1.35	1.20–1.51	16.0	0.953	0.938–0.968	15.9	0.976	0.961–0.991
Smoking^f
Non-smoking	4958	1.04	Ref.		0.909	Ref.		16.7	Ref.		16.3	Ref.
Smoking	571	0.930	0.875	0.806–0.950	0.838	0.901	0.830–0.978	16.1	0.969	0.958–0.980	16.1	0.988	0.977–0.999

^aMethod A (Cobas 8000, Roche Diagnostics). ^bMethod B (ADVIA Centaur XPT, Siemens Healthineers). ^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.