LOW-BIRTH-WEIGHT AND PREECLAMPSIA IN PREGNANCIES COMPLICATED BY HYPERTHYROIDISM

Objective: To determine whether control of hyperthyroidism during preg nancy reduces the risk of low birth weight infants and severe preeclam psia. Methods: Labor, delivery, and postpartum records of 181 hyperthy roid women were reviewed for maternal and fetal outcomes. Subjects wer e separated into three groups based on their thyroid status: controlle d (n = 34), including women who were euthyroid at presentation and del ivery; controlled during pregnancy (n = 90), including women who were hyperthyroid at presentation and euthyroid at delivery; and uncontroll ed (n = 57), including women who were hyperthyroid at presentation and delivery. Results: The risk of low birth weight infants was 0.74 (95% confidence interval [CI] 0.18-3.08) among controlled women, 2.36 (95% CI 1.36-4.12) among women who were controlled during pregnancy, and 9 .24 (95% CI 5.47-15.6) among women who were uncontrolled during pregna ncy compared to the incidence among nonhyperthyroid mothers. The risk of severe preeclampsia was significantly higher (odds ratio 4.74, 95% CI 1.14-19.7) among uncontrolled women compared with those who were co ntrolled during their pregnancies. Elevated TSH-receptor antibody leve ls were not related to preeclampsia. Maternal thioamide therapy did no t adversely affect neonatal outcomes. Conclusion: Lack of control of h yperthyroidism significantly increases the risk of low birth weight in fants and severe preeclampsia.