3.4. Change in Vitamin D Level Does Not Impact Microbiome Diversity
Comparing participants by the change in their vitamin D level allows for an assessment of the impact of vitamin D over a relatively short period (between weeks 10–18 and weeks 32–38 of pregnancy) on the microbiome and accounts for potential lack of adherence to the vitamin D supplementation treatment assignment. All the vitamin D level change analyses were adjusted for the participants’ baseline vitamin D level, in addition to their race and education. We found no significant associations between the participants’ vitamin D change and their microbiome richness for any of the alpha diversity indices that we analyzed. We also found no significant associations with the women’s microbiome composition for any of the analyzed beta diversity measurements. This suggests that the microbiome richness and composition are robust to changes in the vitamin D level during pregnancy.