Comparative Serum Magnesium Levels among Fertile and Infertile Women Attending a Tertiary Hospital in Northwestern Nigeria

Background: Magnesium is an essential micronutrient involved in numerous physiological processes, including ovarian steroidogenesis, follicular development, oocyte maturation, and reproductive hormone regulation. Evidence regarding its association with female infertility remains limited in sub-Saharan Africa. This study compared serum magnesium levels between fertile and infertile women attending a tertiary hospital in northwestern Nigeria and identified factors associated with low serum magnesium levels.Methods: A hospital-based comparative cross-sectional study was conducted among 200 women (100 infertile and 100 fertile) attending Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria. Participants were selected using systematic random sampling. Serum magnesium concentrations were determined using the xylidyl blue colorimetric method. Data were analysed using descriptive statistics, independent samples t-test, chi-square test, and multivariable logistic regression. Statistical significance was set at p < 0.05.Results: The overall mean serum magnesium concentration was 0.61 ± 0.12 mmol/L. Fertile women had significantly higher mean serum magnesium levels than infertile women (0.68 ± 0.11 vs. 0.55 ± 0.08 mmol/L). Low serum magnesium was significantly associated with older age, overweight/obesity, physical inactivity, infertility, and low serum calcium and vitamin D levels (all p < 0.05). After adjustment for potential confounders, increasing age (p = 0.014) and infertility status (adjusted OR = 20.23, 95% CI: 9.74–42.03; p < 0.001) remained independent determinants of low serum magnesium levels.Conclusion: Women with infertility had significantly lower serum magnesium concentrations than fertile women. Increasing age and infertility independently predicted low serum magnesium status. Routine assessment of serum magnesium during infertility evaluation may facilitate the identification of potentially modifiable nutritional deficiencies, although prospective studies are needed to establish causality and evaluate the benefits of magnesium supplementation.