Vitamin D Status Affects Fetal Growth Patterns

TOPLINE:

First trimester maternal 25-hydroxyvitamin D (25(OH)D) concentrations below 40 nmol/L are associated with 4.35 times higher risk for preterm birth. Higher first trimester 25(OH)D levels show positive correlation with fetal linear growth patterns.

METHODOLOGY:

• Researchers conducted a secondary analysis of data from a multisite prospective cohort study involving 351 nulliparous pregnant women in the United States, measuring the serum 25(OH)D level at 6-13 weeks and 16-21 weeks of gestation.
• Analysis included fetal growth measurements by ultrasound at 16-21 weeks and 22-29 weeks of gestation, along with neonatal anthropometric measures at birth, with researchers constructing fetal growth curves using length, weight, and head circumference z-scores.
• Participants were randomly selected to achieve a sample representative of the original distribution with 16% adverse pregnancy outcomes and 84% without adverse outcomes, following specific inclusion criteria including age ≥ 18 years and body mass index ≥ 18.5.

TAKEAWAY:

• Each 10 nmol/L increase in the first trimester 25(OH)D level was associated with a 0.05 (95% CI, 0.01-0.10) increase in length-for-age z-score.
• Participants with the first trimester 25(OH)D level 80 nmol/L.
• First trimester vitamin D insufficiency was prevalent in 20% of participants, with a mean 25(OH)D concentration of 68.1 (SD, 21.0) nmol/L.
• Second trimester 25(OH)D measurements showed no significant associations with fetal growth patterns or pregnancy outcomes.

IN PRACTICE:

“These findings were observed in a study population in which 80% of pregnant females met criteria for vitamin D sufficiency in the first trimester. Few studies have examined fetal growth patterns in relation to early pregnancy maternal vitamin D status, and ours is the first study we are aware of to examine multiple time points of early pregnancy maternal 25(OH)D in association with fetal growth. Our findings suggest that the first trimester (or preconception to increase first trimester vitamin D status) may represent a critical time point for intervention in females with deficiency.” the authors of the study wrote.

SOURCE:

This study was led by Celeste Beck, Department of Nutritional Sciences, Pennsylvania State University in University Park, Pennsylvania. It was published online in The American Journal of Clinical Nutrition.

LIMITATIONS:

According to the authors, the study was limited by a small overall sample size and few participants with vitamin D concentrations below 30 nmol/L, which restricted their ability to compare fetal growth and birth outcomes for participants with very low vitamin D status. The small numbers of small-for-gestational age and preterm birth cases also limited the number of covariates that could be adjusted for in statistical models.

DISCLOSURES:

This study received support from the US Department of Health and Human Services, National Institutes of Health, and Eunice Kennedy Shriver National Institute of Child Health and Human Development. The authors reported no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.