Table 1.

Significance (P values) of associations between fetal age, sex, smoke exposure, high maternal BMI, and their interactions (two-way and three-way analyses), in circulating plasma hormones (T3, T4, TSH) and plasma thyroid hormone-binding proteins (ALB, TTR, TBG)

Interactions:	3-way	2-way				1-way
Smoke effect	Age-sex-SE	Dataset splits	Age-sex	Age-SE	Sex-SE	Age	Sex	SE
T3 (nM)	0.38		0.55	0.56	0.85	0.002 (↑)	0.027 (+ 1.4 fold ♂)	0.67
T4 (nM)	0.098		0.65	0.030	0.89	N/A	N/A	Interaction
		Exposure split
		C	0.19	N/A	N/A	0.002 (↑)	0.84	N/A
		SE	0.38	N/A	N/A	< 0.00001 (↑)	0.96	N/A
T3/T4 ratio	0.65		0.16	0.86	0.79	0.0004 (↓)	0.027 (+ 1.4 fold ♂)	0.72
`TSH (μIU/ml)	0.003	Sex split
		♂	N/A	0.23	N/A	0.28	N/A	0.47
		♀	N/A	0.003	N/A	0.092 (↓C)	N/A	Interaction
		Exposure split
		C	0.12	N/A	N/A	0.24	0.14	N/A
		SE	0.008	N/A	N/A	0.017 (↑♀)	Interaction	N/A
ALB	0.63		0.16	0.58	0.1	< 0.00001 (↑)	0.35	0.420
TTR	0.20		0.11	0.81	0.41	0.17	0.17	0.63
TBG	0.11		0.34	0.14	0.58	0.0022 (↑)	0.89	0.13
BMI effect	Age-Sex-BMI		Age-sex	Age-BMI	Sex-BMI	Age	Sex	BMI
T3 (nM)	0.21		0.86	0.87	0.49	0.002 (↑)	0.021 (+ 1.4 fold ♂)	0.53
T4 (nM)	0.87		0.71	0.85	0.76	< 0.0001 (↑)	0.74	0.49
T3/T4 ratio	0.28		0.89	0.99	0.36	0.0003 (↓)	0.013 (+ 1.4 fold ♂)	0.24
TSH (μIU/ml)	0.068		0.16	0.62	0.005	N/A	Interaction	Interaction
		Sex split
		♂	N/A	0.14	N/A	0.25	N/A	0.27
		♀	N/A	0.26	N/A	0.23	N/A	0.0071 (+ 1.6 fold)
ALB	0.74		0.15	0.48	0.72	< 0.00001 (↑)	0.39	0.49
TTR	0.24		0.11	0.48	0.10	0.16	0.15	0.23
TBG	0.95		0.25	0.36	0.34	0.0022 (↑)	0.88	0.13

Data were log-transformed where model residuals departed from normality and/or showed heteroscedasticity. Statistically significant differences (P < 0.05) are shown in italics. C controls, SE smoke-exposed, N/A not applicable