Effects of Levothyroxine on Pregnancy Outcomes in Women With Thyroid Dysfunction: A Meta-analysis of Randomized Controlled Trials.

Context • Subclinical hypothyroidism (SCH) in pregnancy can be associated with increased complications in pregnant women and neurocognitive deficits in fetuses. Two recently published meta-analyses investigated the effects of levothyroxine (LT4) supplementation on pregnancy outcomes but did not report adverse complications and neonatal outcomes. Objectives • The study intended to assess the effects of LT4 supplementation in the treatment of pregnant women with thyroid dysfunction. Design • The research team performed a meta-analysis of randomized controlled trials (RCTs) published in PubMed, Embase, Web of Science, Chinese BioMedical Literature Service System, and China National Knowledge Infrastructure databases. Participants • Participants were infertile women who had SCH or were TPO antibody positive and who participated in the RCTs examined in the study. Intervention • The participants in the RCTs in the intervention groups received LT4 supplementation and the control groups received a placebo or no treatment. Outcome Measures • The main outcome measures included maternal outcomes-delivery rate, miscarriage rate, fertilization rate, clinical pregnancy rate, preeclampsia, gestational diabetes, and gestational hypertension-and neonatal outcomes-preterm delivery, lower birth weight, intrauterine growth restriction, neonatal death, and congenital malformations. Results were expressed as risk ratios with 95% confidence intervals. Results • A total of 14 RCTs involving 1918 patients were included in the meta-analysis. Compared with control treatments, LT4 supplementation significantly increased the delivery, clinical pregnancy, and fertilization rates. Moreover, LT4 significantly reduced the miscarriage rate, gestational diabetes, and gestational hypertension, but not preeclampsia. For the neonatal outcomes, the study found that the LT4 group had fewer preterm deliveries, birth weights <2500 g, deaths, and congenital malformations.
CONCLUSIONS: LT4 supplementation showed beneficial effects in pregnancy outcomes among patients with thyroid dysfunction. Thus, LT4 should be recommended to improve clinical pregnancy outcomes in women with thyroid dysfunction.