Strengths and Limitations
REGRESSION, PLAGUES
The strengths of this study include the testing of several areas of neurodevelopment, including motor, academic, and language domains, using a validated instrument. Our findings add to a growing body of literature on this topic, supporting some recent studies but contradicting others. Additionally, the inclusion of total circulating 25(OH)D concentration in regression models as an indicator of vitamin D status, in addition to using the treatment group, helps mitigate the issue of adherence to supplementation, which plagues many studies with the inherent variability of vitamin D status at baseline as is with all nutrient studies [Other strengths of the study include the detailed information about the mother’s health during pregnancy and of the offspring collected during annual research visits, as well as the diverse study cohort that included Black American and Hispanic mothers and their offspring. Additionally, while it is possible that differences in vitamin D status during pregnancy and early childhood could exist due to outside sources of vitamin D including sunlight or diet, the inclusion of total circulating 25(OH)D in models as an indicator of vitamin D status to nullify these potential confounders is ultimately a strength of the study.Potential limitations of this study include the smaller sample size, specifically for individual genotypes for VDBP analysis. Additionally, while we were able to control for maternal education in the regression models and showed that the impact of vitamin D on neurodevelopment persisted, we were unable to measure parental intelligence, which could be a significant confounding factor. We also did not assess environmental factors such as food insecurity, housing, crowding, and potential environmental exposures. In addition, other nutrients that could impact neurodevelopment were not measured and thus represent a potential limitation of this study.