Low Vitamin D in First Trimester Tied to Worse Outcomes

FRIDAY, Feb. 7, 2025 (HealthDay News) — Low vitamin D levels during the first trimester of pregnancy are associated with higher rates of preterm birth and decreased fetal length, according to a study published online in the February issue of the American Journal of Clinical Nutrition.

Celeste Beck, Ph.D., M.P.H., from Pennsylvania State University in University Park, and colleagues examined whether first- and second-trimester maternal vitamin D status was associated with fetal growth patterns and pregnancy outcomes. The analysis included 351 participants with vitamin D measurements taken at six to 13 and 16 to 21 weeks of gestation.

The researchers found that vitamin D insufficiency (25-hydroxyvitamin D [25(OH)D] <50 nmol/L) was prevalent in 20 percent of participants in the first trimester. In the first trimester, each 10 nmol/L increase in 25(OH)D was associated with a 0.05 increase in length-for-age z-score but was not associated with weight or head circumference. Using the cutoff of <50 nmol/L, there were no differences in the risk for preterm birth or small for gestational age. However, among participants with first-trimester 25(OH)D <40 nmol/L compared with ≥80 nmol/L, the risk for preterm birth was 4.35 times higher. There was no association for second-trimester 25(OH)D and fetal growth patterns or with pregnancy outcomes.

“This research indicates that vitamin D levels — along with iron, folate, and other essential nutrients in pregnancy — should be monitored and understood by obstetricians and women early on to promote healthy birth outcomes,” Beck said in a statement.

Abstract/Full Text