First-trimester serum retinol quintiles and pregnancy outcomes in a Chinese prospective cohort

To examine the association of serum vitamin A levels in early pregnancy with the risk of adverse pregnancy outcomes in Chinese women. This prospective cohort study was conducted in the Department of Gynecology and Obstetrics at Shenzhen Nanshan People's Hospital from 2019 to 2020. Serum retinol concentrations were measured during the first trimester (the first 6–13 weeks) of pregnancy, and pregnancy outcomes were recorded in the hospital information system. Serum retinol concentrations were categorized into the following quintiles: Q1 ≤ 0.57 μmol/L, 0.57 < Q2 ≤ 0.63 μmol/L, 0.63 < Q3 ≤ 0.69 μmol/L, 0.69 < Q4 ≤ 0.82 μmol/L, and 0.82 < Q5 ≤ 2.50 μmol/L. The participants with serum retinol concentrations in the lowest quintile were used as the reference group. Statistical analysis was performed using multivariate logistic regression. A total of 1,077 singleton pregnancies were included. After multivariable adjustment, serum retinol levels in the highest quintile (Q5) were associated with a significantly lower risk of gestational diabetes mellitus [odds ratio (OR): 0.50; 95% confidence interval (CI): 0.31–0.81]. Similarly, compared with the lowest quintile (Q1), the highest quintile (Q5) was associated with a reduced risk of low birth weight (OR: 0.26; 95% CI: 0.07–0.96). Moreover, the fourth quintile (Q4) was associated with a decreased risk of small for gestational age compared with Q1 (OR: 0.32; 95% CI: 0.12–0.82). In contrast, retinol levels in Q5 were associated with an increased risk of emergency cesarean section compared with Q1 (OR: 2.31; 95% CI: 1.26–4.26). Higher maternal serum retinol levels in the first trimester were associated with a reduced risk of gestational diabetes mellitus and low birth weight, but an increased risk of emergency cesarean section.