Table 2.

Pregnancy outcomes by TSH levels and presence of anti-thyroid antibodies among women with normal fT4 (0.7 to 1.85 ng/dL)

	Model	TSH (TSH ≥ 2.5 mIU/L versus < 2.5 mIU/L)	Anti-thyroid antibodies (Positive versus negative)
		Among Pregnancies (>20 weeks) RR (95% CI)	Among Pregnancies (>20 weeks) RR (95% CI)
Preterm Delivery (n =51)	Unadjusted	0.76 (0.40, 1.45)	1.29 (0.67, 2.48)
	Adjusted	0.78 (0.41, 1.48)	1.28 (0.66, 2.48)
Spontaneous Preterm Delivery (n =18)	Unadjusted	0.54 (0.15, 1.92)	0.31 (0.04, 2.44)
	Adjusted	0.59 (0.17, 2.10)	0.34 (0.04, 2.71)
Medically Indicated Preterm Delivery (n =28)	Unadjusted	0.90 (0.39, 2.08)	2.05 (0.93, 4.51)
	Adjusted	0.89 (0.39, 2.05)	1.90 (0.86, 4.19)
Gestational Diabetes (n =22)	Unadjusted	1.41 (0.59, 3.37)	1.63 (0.62, 4.28)
	Adjusted+	1.27 (0.50, 3.20)	1.32 (0.46, 3.77)
Pre-eclampsia (n =57)	Unadjusted	1.26 (0.74, 2.14)	1.19 (0.63, 2.26)
	Adjusted+	1.16 (0.63, 2.15)	1.00 (0.47, 2.09)

Adjusted for age and BMI

Models restricted to women who had an ongoing pregnancy >20 weeks, with inverse probability weights used to control for potential selection bias introduced by restricting to women who achieved pregnancy. Weights were based on factors associated with becoming pregnancy, including age, parity, marital status, number of prior losses and treatment assignment. Weighted log-binomial regression was used to estimate risk ratios and 95% confidence intervals.

⁺Odds Ratio used when relative risks would not converge