Assessment of serum calcium levels in non-pregnant healthy women and normotensive pregnant women: a hospital-based cross-sectional study

Substantial evidence has associated maternal hypocalcemia with high blood pressure, pregnancy-induced hypertension, and pre-eclampsia. Women from low- and middle-income countries (LMICs) like Nigeria are more likely to have micronutrient deficiencies such as hypocalcemia resulting from suboptimal calcium intake. This study evaluated the mean serum calcium levels difference between non-pregnant women of reproductive age and normotensive pregnant women within the first twenty weeks of gestation at the Lagos University Teaching Hospital. This was a hospital-based cross-sectional study. Seventy-five (75) healthy non-pregnant women and an equal number of pregnant women within the first twenty weeks of gestation were recruited. The serum calcium levels of the two groups were determined and compared. Chi-square and Fisher’s exact tests were used to test the associations between categorical variables. Students’ t-test and Mann-Whitney U test were used to compare means or medians of continuous variables, depending on their distribution. P-values less than 0.05 were considered statistically significant. The mean serum calcium level was significantly higher in non-pregnant (2.5 ± 0.14mmol/L) than in pregnant (2.20 ± 0.17mmol/L) women ( p = 0.048), and the prevalence of hypocalcemia was lower among the non-pregnant women when compared with the pregnant women (44.0% vs. 49.3%; p = 0.6236). Our findings suggest that, despite lower average serum calcium levels during pregnancy, the proportion of women classified as hypocalcemia remains comparable between non-pregnant and pregnant women. We recommend conducting larger, possibly longitudinal studies to elucidate the clinical significance of lower serum calcium levels during pregnancy and to determine if transient changes would impact maternal or fetal outcomes. Meanwhile, efforts should be made to evaluate the need for routine calcium supplementation during pregnancy on an individual basis, particularly in settings where dietary calcium intake may be inadequate.