Association between inadequate weight gain according to the institute of medicine 2009 guidelines and pregnancy outcomes in women with thyroid disorders.

Purpose: Gestational weight gain (GWG) is an important contributor to pregnancy outcomes in the general obstetric population and different subgroups. The corresponding information in women with thyroid conditions is limited. We aimed to evaluate the relationship between GWG according to institute of medicine (IOM) and pregnancy outcomes in women with thyroid disorders.

Methods: We performed a retrospective analysis of 620 pregnant women either treated with levothyroxine (N = 545) or attended because of hyperthyroidism during pregnancy (N = 75).

Results: The associations between GWG according to IOM and pregnancy outcomes were present both in women treated with thyroid hormone and women followed by hyperthyroidism, most of them related to the fetal outcomes. In women treated with levothyroxine, insufficient GWG was associated with gestational diabetes mellitus (GDM) (odds ratio (OR) 2.32, 95% confidence interval (CI) 1.18, 4.54), preterm birth (OR 2.31, 95% CI 1.22, 4.36), small-for-gestational age newborns (OR 2.38, 95% CI 1.09, 5.22) and respiratory distress (OR 6.89, 95% CI 1.46, 32.52). Excessive GWG was associated with cesarean delivery (OR 1.66, 95% CI 1.10, 2.51) and macrosomia (OR 2.75, 95% CI 1.38, 5.49). Large-for-gestational age newborns were associated with both insufficient GWG (OR 0.25, 95% CI 0.11, 0.58) and excessive GWG (OR 1.80, 95% CI 1.11, 2.92). In women followed by hyperthyroidism, excessive GWG was associated with large-for-gestational age newborns (OR 5.56, 95% CI 1.03, 29.96).

Conclusion: GWG according to IOM is associated with pregnancy outcomes both in women treated with thyroid hormone and women followed by hyperthyroidism.