Subsequent pregnancy outcomes in women previously diagnosed with subclinical hypothyroidism

To evaluate subsequent pregnancy outcomes in women previously identified during an index pregnancy to have subclinical hypothyroidism (SCH).

From 2000 to 2003, thyroid analytes were measured in 17,298 women. Using their index pregnancy thyroid-analyte classification, pregnancy outcomes were compared between the returning cohorts.

There were 6,985 women previously screened and subsequently delivered at our hospital though 2011 with 230 (3.3%) designated to have SCH and 6,645 (95.1%) euthyroid. Significant differences between the two cohorts included risk for diabetes (odds ratio [OR] 1.8, 95% confidence interval [CI] 1.2 to 2.7, p = 0.005), gestational diabetes (OR 1.74, 95% CI 1.13 to 2.69, p = 0.015), and stillbirth (OR 3.5, 95% CI 1.05 to 11.68, p = 0.042). After adjustment, the increased likelihood of diabetes (adjusted OR 1.58, 95% CI 1.04 to 2.40, p = 0.032) and stillbirth (adjusted OR 3.41, 95% CI 1.01 to 11.49, p = 0.048) persisted.

Women identified during a previous pregnancy with SCH are at increased risk for some adverse perinatal outcomes during a subsequent pregnancy.