The association between maternal multivitamin intake and premature birth.

In urban settings, unsupervised maternal multivitamin use is common, but its impact on premature birth (PTB) remains unclear. We conducted a secondary analysis of a nested case-control study within a population-based prospective cohort in Wuhan, China (2011-2013), including 6656 births. Maternal multivitamin intake was assessed during the preconceptional period (three months before pregnancy) and the prenatal period (during pregnancy). Multivariable logistic regression models were used, adjusting for socio-demographic, lifestyle, and clinical factors. Multivitamin use during both the preconceptional and prenatal periods was associated with higher odds of medically-indicated PTB (adjusted OR: 1.54, 95% CI 1.18, 2.03). Causality cannot be confirmed due to limited exposure assessment, residual confounding, and potential reverse causation. Maternal intake behaviors and whether multivitamins provide adequate levels of key nutrients may also influence outcomes, highlighting the need for further investigation. While multivitamins are important, they cannot replace medical treatments for preventing PTB. Monitoring maternal vitamin levels and providing clear guidance from healthcare providers are essential to ensure safe and effective use and to protect maternal and neonatal health.