1. Introduction
dysbiosis, asthma/allergic disease
LATE PREGNANCY, ASTHMA, VITAMIN D DEFICIENCY, REGRESSIONS
Shifts in the maternal gut microbiome and vitamin D deficiency during pregnancy have been associated, separately, with health problems for both the mother and the child. Yet, they have rarely been studied simultaneously. Here, we analyzed the gut microbiome (from stool samples obtained in late pregnancy) and vitamin D level (from blood samples obtained both in early and late pregnancy) data of pregnant women in the Vitamin D Antenatal Asthma Reduction Trial (VDAART), a randomized controlled trial of vitamin D supplementation during pregnancy, to investigate the association of vitamin D status on the pregnant women’s microbiome. To find associations, we ran linear regressions on alpha diversity measures, PERMANOVA tests on beta diversity distances, and used the ANCOM-BC and Maaslin2 algorithms to find differentially abundant taxa. Analyses were deemed significant using a cut-off Vitamin D has been strongly associated with many conditions of human health. Initially, it was discovered to promote bone health [The gut microbiome is composed of trillions of microbes that collectively influence the health of its host [The gut microbiome composition changes with age and is naturally modified during several stages of life. During pregnancy, the microbiome shift often resembles diseased states or dysbiosis that, surprisingly, instead of leading to a decline in fitness, promotes homeostasis [The impact on the offspring of the maternal vitamin D level in serum and of vitamin D consumption during pregnancy has been studied several times, establishing associations with the children’s microbiome and with outcomes such as changes in the immune system modulation, asthma/allergic disease incidence, likelihood of Here, we analyze the 16S rRNA data generated from stool samples of 114 pregnant women in the Vitamin D Antenatal Asthma Reduction Trial (VDAART), a multi-site randomized, double-blind, placebo-controlled trial of vitamin D supplementation during pregnancy, to look for associations between the participants’ vitamin D status and their gut microbiome during the third trimester of pregnancy. We use three different measures for the vitamin D status: (1) baseline vitamin D level, (2) treatment assignment, and (3) change in vitamin D level over the trial period. In the following, we present three key findings. First, the baseline vitamin D level is associated with the gut microbiome composition. Second, the gut microbiome is robust enough such that the vitamin D supplementation (even with up to 4400 IU cholecalciferol daily) during pregnancy does not significantly modify it. Third, 