Maternal Thyroid Disease and Preterm Birth: Systematic Review and Meta-Analysis

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Perinatal Medicine

Background:

• Thyroid disease in pregnancy is increasingly prevalent due to rising maternal age.
• Existing evidence linking thyroid disease and preterm birth is inconsistent due to study limitations.

Purpose of the Study:

• To conduct a meta-analysis evaluating the association between various maternal thyroid conditions and preterm birth.
• To synthesize data on overt hypothyroidism, subclinical hypothyroidism, hyperthyroidism, and isolated hypothyroxinemia concerning preterm delivery.

Main Methods:

• A comprehensive literature search was conducted on PubMed and Embase databases.
• Included studies were prospective cohort or case-control studies reporting on maternal thyroid disease and preterm birth.
• A fixed-effects model was used to calculate pooled odds ratios (OR) for preterm delivery.

Main Results:

• The meta-analysis included 15 studies with over 2.5 million participants.
• Overt hypothyroidism was associated with a significant increase in preterm birth risk (OR, 1.19; 95% CI, 1.12-1.26).
• Hyperthyroidism also showed a significant association with preterm birth (OR, 1.24; 95% CI, 1.17-1.31).
• Subclinical hypothyroidism and isolated hypothyroxinemia did not demonstrate a significant link to increased preterm birth.

Conclusions:

• Overt hypothyroidism and hyperthyroidism in pregnant individuals are linked to a statistically significant, albeit small, increase in preterm birth rates.
• Subclinical hypothyroidism and isolated hypothyroxinemia do not appear to pose a similar risk for preterm delivery.