Obianuju Onuoha, Ph.D. Research

Doctor of Philosophy in Medical Nutrition Science (2023-2026)

Vitamin A during pregnancy is essential for fetal growth and development, immune function, vision, cellular differentiation, signaling and gene regulation. Inadequate dietary vitamin A intake remains a major contributor to poor vitamin A status, and marginal or deficient status during pregnancy has been associated with adverse maternal and infant outcomes, including anemia, low birth weight, preterm birth, impaired immunity and increased infection risk.

Although national data suggest that some U.S. pregnant women have insufficient vitamin A intake even when prenatal supplements are included, less is known about whether dietary intake alone accurately reflects vitamin A status during pregnancy.

Onuoha’s dissertation research addressed this gap by quantifying plasma retinol as a biomarker of vitamin A status in a U.S. Midwestern cohort of pregnant women and examining its relationship with dietary vitamin A intake, supplement use, maternal characteristics and pregnancy outcomes.

Her findings showed that vitamin A insufficiency was present in a subset of women despite most participants meeting the estimated average requirement for vitamin A intake. Plasma retinol status was not strongly predicted by total vitamin A intake (diet plus supplement), while beta-carotene intake was lower among women with lower plasma retinol concentrations. Plasma retinol was positively associated with hemoglobin concentrations but was not significantly associated with anemia diagnosis or selected adverse pregnancy outcomes.

These findings highlight the value of biomarker-based assessment in understanding vitamin A status during pregnancy and suggest that dietary intake alone may not fully identify women at risk for marginal vitamin A status.

In June 2024, Onuoha received the School of Health Professions Ph.D. Research Award, which provided funding support for this dissertation project.

Visit Onuoha's LinkedIn profile