Serum Calcium Status among Fertile and Sub fertile Women in Northwestern Nigeria: A Comparative Hospital-Based Study

Abstract

Calcium plays an essential role in female reproductive physiology through its involvement in folliculogenesis, steroidogenesis, oocyte maturation, fertilization, and embryo development. However, evidence regarding the relationship between serum calcium status and female subfertility remains limited, particularly in sub-Saharan Africa. To compare serum calcium concentrations between fertile and subfertile women attending the Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto, Nigeria, and determine the association between serum calcium status and selected sociodemographic and clinical characteristics. A comparative hospital-based cross-sectional study was conducted among 200 women comprising 100 fertile and 100 subfertile participants. Sociodemographic and clinical information was obtained using a structured interviewer-administered questionnaire. Venous blood samples were collected for serum calcium estimation using the O-cresolphthalein Complexone colorimetric method. Data were analysed using IBM SPSS Statistics, with statistical significance set at p < 0.05. The mean serum calcium concentration was significantly higher among fertile women than subfertile women (2.12 ± 0.25 mmol/L vs. 1.93 ± 0.25 mmol/L; p < 0.001). Low serum calcium was significantly associated with subfertility, age, body mass index, religion, physical activity, and alcohol intake. Subfertile women were more frequently overweight or obese and were generally older than fertile women. Subfertile women had significantly lower serum calcium concentrations than fertile women, suggesting that altered calcium homeostasis may be associated with female subfertility. Assessment of nutritional status may complement conventional infertility evaluation. Further prospective studies are needed to establish causality and evaluate whether correction of calcium deficiency improves fertility outcomes.