Vitamin D Deficiency Associated with Increased Risk of Preterm Birth in Pregnant Black Women 

by | Dec 19, 2023 | 2023, Pregnancy and Lactation, Vitamin D - Recommended Levels, Women's Health

Written by Taylor Woosley, Staff Writer. Women with vitamin D deficiency were 2.80 times as likely to have a PTB compared to women with sufficient vitamin D levels (p ≤ 0.01). 

vitamin DPreterm birth (PTB; birth <37 weeks gestation) is the second leading cause of infant mortality in the United States1. The rates of PTB for U.S. non-Hispanic Black women who give birth prematurely are 1.5 times the rate of non-Hispanic White women2. Several risk factors (previous PTB, pre-pregnancy medical conditions), including some social determinants of health, have been demonstrated to contribute to these pathways3.

Vitamin D status during pregnancy is the most important stage of the lifecycle, as the fetus completely relies on this source during this period for its development4. Vitamin D requirements are increased during pregnancy to adapt to heightened physiological demands in the mother5.  Research has shown that adverse pregnancy outcomes, such as preterm birth and low birth weight, can be associated with low vitamin D levels during pregnancy6.

Woo et al. conducted a nested case-control study to analyze whether vitamin D deficiency in early pregnancy increases the risk of PTB in later pregnancy in a cohort of Black women while adjusting for other confounders. Data used was from a subset of the Biosocial Impact on Black Births (BIBB) study. Subject inclusion consisted of being an African American or Black woman, aged 18-45 years old, who had a singleton pregnancy and were enrolled between 8 and 29 weeks of gestation. Birth and medical history information was obtained from maternal medical records and the subjects completed demographic questionnaires and provided blood samples between 8 and 25 weeks of gestation for analysis.

A subsample of 57 women with PTB with completed questionnaires and blood samples for measuring vitamin D were included in the final analysis. Furthermore, a subsample of 118 women with term birth and available questionnaire and blood sample data were included in the analysis to maintain an approximate 2:1 ratio of term birth to PTB. BMI was measured at the first prenatal visit. Depressive symptoms were assessed using The Center for Epidemiologic Studies Depression Scale (CES-D).

Independent samples t-tests and χ2 tests were utilized to investigate whether there were statistically significant differences in maternal characteristics between PTB women and women with term birth. Significant findings of the binary logistic regression analysis shows that only vitamin D was a predictor of PTB. Women with vitamin D deficiency were 2.80 times as likely to have a PTB compared to women with sufficient vitamin D levels (OR = 2.80, 95% CI: 1.40, 5.59, p ≤ 0.01). A slightly weaker effect of vitamin D was found (OR = 2.74, 95% CI: 1.35-5.54) after adjusting for depressive symptoms and hypertensive disorders of pregnancy.

Results of the study show that vitamin D deficiency alone was a significant predictor of PTB in a cohort of Black women. Further research on the use of vitamin D supplementation to reduce PTB risk is necessary to better comprehend its impact. Study limitations include the small sample size, the lack of dietary data on participants, and the large range of gestational age at blood draw.

Source: Woo, Jennifer, Thomas Guffey, Rhonda Dailey, Dawn Misra, and Carmen Giurgescu. “Vitamin D Status as an Important Predictor of Preterm Birth in a Cohort of Black Women.” Nutrients 15, no. 21 (2023): 4637.

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

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Posted December 19, 2023.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

References:

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