Table 3.

Association of adverse pregnancy outcomes with first-trimester IMH, stratified by maternal age and pre-pregnancy BMI

Outcome	Stratification		Incidence (%)		Crudea		Adjustedb		P for Interactionc
			IMH group (n = 2,001)	Euthyroid (n = 35,733)	OR (95% CI)	P value	OR (95% CI)	P value
Preterm birth	Age	< 35 (y)	5.4	4.5	1.21 (0.97 ~ 1.52)	0.095	1.11 (0.87 ~ 1.43)	0.399	0.073
		≥ 35 (y)	9.7	6.3	1.61 (1.15 ~ 2.25)	0.006 *	1.67 (1.16 ~ 2.40)	0.006 *
	BMI	< 24 (kg/m2)	6.0	4.6	1.29 (1.02 ~ 1.63)	0.030 *	1.23 (0.97 ~ 1.55)	0.084	0.725
		≥ 24 (kg/m2)	7.9	5.8	1.37 (0.92 ~ 2.05)	0.121	1.30 (0.87 ~ 1.96)	0.201
GDM	Age	< 35 (y)	16.5	9.2	1.94 (1.69 ~ 2.23)	< 0.001 *	1.42 (1.21 ~ 1.66)	< 0.001 *	0.146
		≥ 35 (y)	22.9	18.1	1.34 (1.06 ~ 1.70)	0.013 *	1.14 (0.88 ~ 1.48)	0.331
	BMI	< 24 (kg/m2)	15.4	9.0	1.66 (1.42 ~ 1.94)	< 0.001 *	1.40 (1.19 ~ 1.64)	< 0.001 *	0.260
		≥ 24 (kg/m2)	27.0	20.1	1.29 (1.01 ~ 1.65)	0.043	1.20 (0.93 ~ 1.54)	0.162
Preeclampsia	Age	< 35 (y)	3.2	1.9	1.66 (1.24 ~ 2.24)	< 0.001 *	1.37 (0.99 ~ 1.90)	0.055	0.264
		≥ 35 (y)	5.1	2.5	2.12 (1.33 ~ 3.38)	0.002 *	1.92 (1.15 ~ 3.20)	0.013 *
	BMI	< 24 (kg/m2)	2.7	1.7	1.54 (1.09 ~ 2.17)	0.014 *	1.36 (0.96 ~ 1.93)	0.084	0.617
		≥ 24 (kg/m2)	6.8	4.2	1.62 (1.05 ~ 2.49)	0.030 *	1.72 (1.11 ~ 2.67)	0.016 *
Emergency CS	Age	< 35 (y)	8.1	6.2	1.34 (1.11 ~ 1.62)	0.002 *	1.02 (0.83 ~ 1.24)	0.873	0.165
		≥ 35 (y)	7.3	4.7	1.58 (1.08 ~ 2.32)	0.020 *	1.40 (0.94 ~ 2.09)	0.095
	BMI	< 24 (kg/m2)	8.1	6.0	1.13 (0.93 ~ 1.37)	0.234	1.11 (0.91 ~ 1.35)	0.315	0.432
		≥ 24 (kg/m2)	7.3	6.4	0.90 (0.60 ~ 1.35)	0.609	0.94 (0.62 ~ 1.41)	0.747
Fetal distress	Age	< 35 (y)	8.8	4.4	2.11 (1.75 ~ 2.53)	< 0.001 *	1.49 (1.23 ~ 1.81)	< 0.001 *	0.590
		≥ 35 (y)	8.8	4.2	2.23 (1.56 ~ 3.20)	< 0.001 *	1.81 (1.25 ~ 2.64)	0.002 *
	BMI	< 24 (kg/m2)	8.3	4.2	1.62 (1.34 ~ 1.97)	< 0.001 *	1.51 (1.24 ~ 1.84)	< 0.001 *	0.933
		≥ 24 (kg/m2)	10.4	5.5	1.54 (1.09 ~ 2.17)	0.013 *	1.62 (1.15 ~ 2.30)	0.006 *
LBW	Age	< 35 (y)	3.0	2.5	1.18 (0.87 ~ 1.59)	0.291	1.11 (0.79 ~ 1.55)	0.545	0.081
		≥ 35 (y)	4.6	2.9	1.60 (1.00 ~ 2.58)	0.051	1.91 (1.16 ~ 3.15)	0.011 *
	BMI	< 24 (kg/m2)	3.0	2.6	1.15 (0.83 ~ 1.58)	0.403	1.20 (0.87 ~ 1.66)	0.266	0.291
		≥ 24 (kg/m2)	4.5	2.8	1.59 (0.94 ~ 2.68)	0.084	1.55 (0.91 ~ 2.64)	0.105
Macrosomia	Age	< 35 (y)	10.0	5.9	1.79 (1.51 ~ 2.13)	< 0.001 *	1.52 (1.26 ~ 1.84)	< 0.001 *	0.883
		≥ 35 (y)	10.6	6.4	1.74 (1.25 ~ 2.40)	< 0.001 *	1.53 (1.06 ~ 2.20)	0.023 *
	BMI	< 24 (kg/m2)	8.4	5.2	1.73 (1.42 ~ 2.12)	< 0.001 *	1.46 (1.19 ~ 1.80)	< 0.001 *	0.872
		≥ 24 (kg/m2)	16.3	11.5	1.56 (1.16 ~ 2.09)	0.003 *	1.52 (1.13 ~ 2.05)	0.006 *

Abbreviations GDM Gestational Diabetes Mellitus IMH isolated maternal hypothyroxinemia, CS cesarean section, LBW low birth weight, OR Odds Ratio, CI Confidence Interval

^*P < 0.05 was considered statistically significant

^aUnivariate logistic regression was performed using the euthyroid group as the reference

^b Estimates were obtained using multivariate logistic regression models, adjusted for maternal age, pre-pregnancy BMI, gravidity, parity, and educational level

^c P values for interaction evaluated the modifying effects of maternal age and BMI on the association between IMH and pregnancy outcomes