Background: Maternal vitamin D status during pregnancy may influence lung development and risk of childhood wheeze and asthma. We investigated the relationship between prenatal vitamin D and child asthma in a racially diverse cohort with a high burden of vitamin D insufficiency and child asthma.Materials and methods: We included mother-child dyads in the prenatal Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) cohort (2006-2011, Shelby County, Tennessee). Maternal plasma vitamin D [25(OH)D] was measured from second trimester (n = 1091) and delivery specimens (n = 907). At age 4-6 years, we obtained parent report of current child wheeze (symptoms within the past 12 months) and asthma (physician diagnosis and/or medication or symptoms within the past 12 months). We used multivariable logistic regression to assess associations of 25(OH)D and child wheeze/asthma, including an interaction term for maternal race.Results: Median second trimester 25(OH)D levels were 25.1 and 19.1 ng/ml in White (n = 366) and Black women (N = 725), respectively. We detected significant interactions by maternal race for second-trimester plasma 25(OH)D and child current wheeze (p = .014) and asthma (p = .011). Odds of current wheeze and asthma decreased with increasing 25(OH)D in dyads with White mothers and increased in dyads with Black mothers, e.g. adjusted odds ratio (95% confidence interval) for asthma: 0.63 (0.36-1.09) and 1.41 (1.01-1.97) per interquartile range (15-27 ng/ml 25[OH]D) increase, respectively. At delivery, protective associations in White dyads were attenuated.Conclusion: We detected effect modification by maternal race in associations between prenatal 25(OH)D and child wheeze/asthma. Further research in racially diverse populations is needed.
Keywords: 25(OH)D; asthma; prenatal programing; race; vitamin D; wheezing.