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

Abstract

Objective: Thyroid disorder is a common endocrine complication in pregnant 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 subclinical hyperthyroidism and hypothyroidism. Methods: Relevant studies in English published between 1990 and 2016 were identified by searching PubMed, Medicine, and Embase databases. Cohort studies that evaluated the association between LBW infants and overt and subclinical hyperthyroidism or hypothyroidism during pregnancy and included a healthy pregnancy reference 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.

Gestation-suppressed serum TSH levels during early pregnancy are not associated with altered maternal and neonatal outcomes

“…Studies published after the publication of the 2017 ATA-GL report contradictory results. On one hand, there were meta-analyses that did not report an impact on IUGR and LBW ( 8 , 13 , 14 ), and on the other hand, original studies and meta-analyses reporting a higher prevalence of PTB ( 3 , 5 ), pre-eclampsia ( 7 ), placental abruption and even a lower risk of abortion ( 6 ). These more recent studies also included women with sTSH levels (and thus not only with low TSH) and considered demographic and obstetric confounders.…”

“…Since the ATA publication in 2017, other studies have associated SH with an increased prevalence of preterm delivery (PTB) ( 3 , 4 , 5 ), pre-eclampsia ( 6 , 7 ) and low birth weight ( 3 ). On the contrary, a meta-analysis did not associate SH with a low-birth weight ( 8 ).…”

Maternal Subclinical Hyperthyroidism and Adverse Pregnancy Outcomes: A Systematic Review and Meta-analysis of Observational Studies

“…Three meta-analyses assessed the adverse pregnancy outcomes in women with subclinical hyperthyroidism. These studies had mainly focused only on preterm delivery, IUGR, and LBW and found no significant association between subclinical hyperthyroidism and these outcomes ( 25 , 30 , 50 ). This meta-analysis of nine studies demonstrated that subclinical hyperthyroidism was not associated with adverse maternal outcomes, such as hypertensive disorders, preterm delivery, and pregnancy loss, neonatal outcomes, such as macrosomia/LGA, and adverse fetal outcomes.…”

“…Several previous systematic reviews and meta-analyses have been published on adverse pregnancy outcomes of thyroid dysfunction so far (8,25,(28)(29)(30)(31); however the majority of them have not reported these outcomes specifically for subclinical hyperthyroidism (8,28,29). Among those ones that included this subgroup of thyroid dysfunction, various feto-maternal outcomes have not been investigated and only intrauterine growth restriction (IUGR) (25) and low birth weight (LBW) (30) have been reported.…”

Maternal Factors Affecting Newborn Weight at Term- A Study in a Referral Hospita

“…However, in studies conducted by Khetua et al, 19 S. Pachauri et al, 22 and Shanti Ghosh et al, 23 it was concluded that maternal haemoglobin played a important role in the neonatal birth weight. In a systemic review and meta-analysis conducted by Gin Chiu et al, 24 it was concluded that hyperthyroidism in pregnancy was associated with a higher increased risk of LBW infants compared with normal thyroid function in pregnancy, whereas, no association was found between LBW newborns and maternal subclinical hyperthyroidism or hypothyroidism.…”