Cord blood 25(OH)D in high-risk pregnancies: An ANCOVA-based analysis in hypertensive disorders, severe anaemia, and gestational diabetes.

BACKGROUND: Cord blood 25-hydroxyvitamin D [25(OH)D] at birth reflects maternal vitamin D availability and maternal-fetal handling. We compared cord 25(OH)D across hypertensive disorders of pregnancy (HDP), severe anaemia, gestational diabetes mellitus (GDM), and healthy controls using ANCOVA to determine whether group differences persisted after accounting for maternal substrate availability. METHODS: This cross-sectional comparative study enrolled 400 primigravida women presenting in active labour at ≥34 weeks gestation: HDP (n = 75), severe anaemia (haemoglobin <7 g/dL; n = 75), GDM (n = 50), and uncomplicated controls (n = 200). The primary ANCOVA adjusted for maternal 25(OH)D and clinical group; a pre-specified sensitivity analysis additionally adjusted for gestational age and birthweight. RESULTS: In the primary ANCOVA, HDP was associated with a cord blood deficit (B = -6.14, p < 0.001) and severe anaemia with a smaller deficit (B = -2.93, p < 0.001); GDM was not significantly different from controls. After additional adjustment for gestational age and birthweight, deficits remained significant for HDP (B = -4.85, p < 0.001) and anaemia (B = -1.95, p = 0.002). No HDP neonate met the pre-specified sufficiency threshold of ≥20 ng/mL (0/75, 0.0%; 95% CI 0.0-4.8%). CONCLUSION: HDP remained associated with substantially lower cord 25(OH)D after adjustment for maternal levels, gestational age, and birthweight. This residual association is compatible with altered maternal-fetal vitamin D handling but, given cross-sectional sampling at delivery and absence of direct placental measurements, does not establish impaired placental transport. Severe anaemia showed a smaller residual deficit; GDM showed no significant deficit.