Relationship between Maternal Vitamin D and Calcium Status and Neonatal Calcium Homeostasis in Pregnancies Complicated by Hypertensive Disorders

Abstract

Background: Hypertensive disorders of pregnancy can lead to maternal and fetal complications and can affect the transfer of nutrients from the placenta. Vitamin D and calcium play a crucial role in maternal mineral balance, fetal skeletal development and neonatal calcium regulation. Changes in maternal vitamin D and calcium levels might consequently influence the development of neonatal hypocalcemia, especially during preeclampsia and other hypertensive disorders.

Objective: To determine the relationship between maternal vitamin D and calcium status and neonatal calcium homeostasis in pregnancies complicated by hypertensive disorders.

Methodology: This analytical cross-sectional study was carried out in January-June 2025 in Khalifa Gul Nawaz Teaching Hospital, Bannu. The pregnant women with hypertensive disorders and neonates were selected by consecutive sampling, with a total number of 75. Serum 25-hydroxyvitamin D, calcium, phosphate, magnesium and albumin levels were measured. Data recorded included: Neonatal birth weight, Apgar scores, cord blood calcium, neonatal serum calcium, phosphate, magnesium, and neonatal hypocalcemia status. Correlation analysis, Chi-square/Fisher’s exact test and multivariable logistic regression were used to evaluate the associations between maternal biochemical status and neonatal calcium homeostasis. One-sided p-value of < 0.05 was regarded as statistically significant.

Results: The mean maternal serum 25(OH)D level was 20.46 ± 8.17 ng/mL, while mean maternal serum calcium was 8.42 ± 0.71 mg/dL. Vitamin D deficiency was observed in 45.3% of mothers and low maternal calcium in 34.7%. The mean neonatal serum calcium concentration was 8.21 ± 0.76 mg/dL, and neonatal hypocalcemia occurred in 25.3% of newborns. Maternal vitamin D and serum calcium were positively correlated with neonatal calcium levels (r = 0.46 and r = 0.52, respectively; both p < 0.001). Neonatal hypocalcemia was significantly more frequent among vitamin D-deficient mothers, mothers with low serum calcium, and women with severe preeclampsia.

Conclusion: Lower maternal vitamin D and calcium levels were significantly associated with impaired neonatal calcium homeostasis in hypertensive pregnancies. Maternal vitamin D deficiency, low calcium status, and severe preeclampsia may identify neonates at increased risk of hypocalcemia and may warrant closer biochemical monitoring after birth.