Maternal Thyroid Disease and Neonatal Low Birth Weight: A Systematic Review and Meta-Analysis

Abstract

Objective: Thyroid disorder is a common endocrine complication in preg-nant women: the association between neonatal low birth weight (LBW) and thyroid dysfunction during pregnancy has not been definitely confirmed. We conduct a systematic literature review and meta-analysis of the adverse fetal complication of LBW in maternal thyroid disease, including overt and sub-clinical hyperthyroidism and hypothyroidism. Methods: Relevant studies in English published between 1990 and 2016 were identified by searching Pub-Med, Medicine, and Embase databases. Cohort studies that evaluated the as-sociation between LBW infants and overt and subclinical hyperthyroidism or hypothyroidism during pregnancy and included a healthy pregnancy refer-ence group were selected. The combined odds ratio (OR) with 95% confidence intervals (CI) were calculated to evaluate this relationship. Results: A total of 11 cohort studies (1,171,052 participants) assessed the association between maternal thyroid disease and LBW infants. An increased risk for LBW in hyperthyroidism pregnancies was demonstrated (OR: 1.30, 95% CI 1.11 -1.54; p = 0.02). No significant increased risk for LBW was detected in subclinical hyperthyroidism (OR 1.03; 95% CI 0.72 -1.48; p = 0.87), or hypothyroidism pregnancies (overt: OR 0.98; 95% CI 0.88 -1.10; p = 0.75; subclinical: OR 1.29; 95% CI 0.81 -2.04; p = 0.28). Conclusion: Data show a higher trend towards an increased risk of LBW among infants from maternal hyperthyroidism pregnancies. No association was seen in subclinical cases of hyperthyroidism or hypothyroidism during pregnancy.