Retrospective analysis of the effects induced by maternal thyroid dysfunction on obstetrical complications and outcomes

Background: Abnormal concentrations of maternal thyroid hormones are risk factors for some obstetrical complications. However, the influence induced by different types of maternal thyroid dysfunction on obstetrical complications and outcomes is still controversial.Methods: A total of 17219 pregnant women were drawn for a thyroid function test, including TSH and fT4. All participants were divided into 7 groups, on the basis of their blood tested results, and their pregnancy outcomes were followed up. The isolated hypothyroxinemia group was further divided into 2 cohorts, according to whether they receive levothyroxine. Pregnant complications and outcomes in two cohorts were observed and analyzed.Results: A total of 2621 (15.22%)were identified to have abnormal thyroid function, including 1150 with subclinical hypothyroidism, 526 with gestational transient thyrotoxicosis (GTT), 419 with subclinical hyperthyroidism, 336 with isolated hypothyroxinemia, 78 with hyperthyroidism and 76 with hypothyroidism. Compare to control group, subclinical hypothyroidism, subclinical hyperthyroidism, isolated hypothyroxinemia and hypothyroidism groups presented higher incidence in one or more complications of pregnancy, while, GTT and drug-controlled hyperthyroidism had little significant effect on pregnancy complications. In isolated hypothyroxinemia group, there were no significant difference outcomes between cohorts using levothyroxine and not treatment.Conclusions: Our results showed a high incidence rate of thyroid dysfunction in pregnant women, and subclinical hypothyroidism is most common, followed by GTT. In general, pregnant women with thyroid dysfunction presented high risk of pregnancy complications. Isolated hypothyroxinemia in pregnant women is a matter of concern and treatment with levothyroxine couldn’t improve pregnancy outcomes and obstetrical complications.