Gestational Selenium Exposure and Neonatal Health Outcomes: A Systematic Review of Mortality, Morbidity, and...

Objectives: This systematic review synthesized the existing literature to evaluate the associations between maternal Selenium (Se) exposure during pregnancy and neonatal outcomes, specifically focusing on parameters of mortality, morbidity, and neurobehavioral development. Methods: PubMed, Embase, and the Cochrane Library were systematically searched from inception through December 2025. For quality appraisal, Cochrane RoB2 and the National Heart, Lung, and Blood Institute of the National Institutes of Health tools for observational studies were applied. Results were qualitatively synthesized. Results: Screening of 2743 unique records and 473 full-text articles yielded 355 papers included in the overarching SeduP project, with 19 specific to this review. Synthesized evidence revealed a lack of consistent evidence of an association between maternal Se status and all-cause neonatal or perinatal mortality (n = 413, 4 studies), combined mortality/morbidity (n = 2753, 2 studies), or infectious-related morbidity (n = 928, 3 studies). Conversely, conflicting findings were observed regarding all-cause neonatal morbidity (n = 68, 2 studies) and neurobehavioral development (n = 1442, 4 studies), while a potentially inverse association was identified exclusively between Se levels and pulmonary-related neonatal morbidity (n = 611, 4 studies). Conclusions: Despite compelling preclinical biological plausibility, clinical data do not support a widespread protective effect of maternal Se status against adverse neonatal outcomes. The existing body of evidence is heavily constrained by moderate to very low quality, driven by small sample sizes, insufficient confounding adjustments, and suboptimal exposure assessment timing at delivery. While localized signals imply potential pulmonary protection alongside risks of excess toxicity, large-scale, standardized prospective cohorts are critically needed to generate clinically actionable data.