Impact of maternal serum 25(OH)D concentration in the third trimester on birth outcomes and cord blood FGF23 levels.

BACKGROUND

Maternal vitamin D concentration has been linked to various health outcomes, but its associations with obstetric outcomes, infant growth, and cord blood cytokines remain inconclusive.

METHODS

We conducted an observational study including 132 pregnant women whose serum 25-hydroxyvitamin D [25(OH)D] levels were measured in the third trimester. After delivery, cord blood cytokines related to fetal growth were measured. Participants were divided into quartiles based on 25(OH)D concentration. Infant anthropometric indicators were analyzed using WHO-standardized Z-scores for length, weight, and head circumference at birth, 3 months, and 6 months. Analysis of variance or the Kruskal-Wallis method was used to compare obstetric complications, neonatal outcomes, and infant growth among the groups.

RESULTS

Maternal serum 25(OH)D concentration in the third trimester exhibited a significant association with infant length, weight, and head circumference up to 6 months, with greatest differences at 6 months. However, the prevalence of obstetric complications did not differ significantly across quartiles. Cord blood fibroblast growth factor 23 (FGF23) levels were positively correlated with maternal serum 25(OH)D concentration and may contribute to fetal growth regulation.

CONCLUSIONS

This study demonstrated a positive association between maternal serum 25(OH)D concentration and early infant growth outcomes. Cord blood FGF23 levels were associated with maternal vitamin D levels and neonatal growth, suggesting a potential role of FGF23 in the underlying mechanism of fetal growth restriction associated with vitamin D deficiency. These findings highlight the relevance of adequate maternal vitamin D status during pregnancy for promoting healthy perinatal growth.