Predictors of Vitamin B-12 Status in Pregnant Chilean Women During the COVID-19 Pandemic: Results of the Chilean Maternal and Infant Cohort Study-II

Background Adequate vitamin B12 (B12) concentrations are essential for optimal pregnancy development. The COVID-19 pandemic may have compromised adequate B12 intake. However, evidence on maternal B12 status and its predictors during the pandemic is scarce. This study aimed to assess serum total B12 (sB12) concentrations in the first or second trimester, and to identify maternal lifestyle, obstetric, and dietary predictors of B12 status among pregnant Chilean women during the COVID-19 pandemic. Methods Between March 2020 and November 2021, pregnant women (≥18 years) were recruited from public healthcare centers in Santiago, Chile, to participate in the Chilean Maternal and Infant Cohort Study-II (CHIMINCs-II). The sB12 concentration was determined in a randomly selected sample of 413 participants who provided blood samples in the first or second trimester, using a chemiluminescent microparticle immunoassay. B12 deficiency was defined as sB12 concentrations <148 pmol/L. Stepwise linear and logistic regression models were used to identify predictors of B12 status. Results The median (IQR) sB12 concentration was 169 (106) pmol/L, and 37% of women had B12 deficiency. Overall, 40% of women had obesity. Women who took prenatal supplements and had a higher income were less likely to have a B12 deficiency ( p <0.05). Higher pre-pregnancy BMI and parity were associated with a higher likelihood of B12 deficiency. Conclusion Maternal B12 deficiency was concentrated among vulnerable groups. Efforts should be made to identify and support these groups before and during pregnancy to improve maternal B12 status, especially under food insecurity scenarios, such as during the COVID-19 pandemic.