There is a growing literature linking gut microbiome to asthma. In the general population, there is a greater microbial diversity among women with no asthma than those with asthma, with a greater abundance of anti-inflammatory taxa and conversely, a greater abundance of pro-inflammatory bacteria among women with asthma. Gut microbiotas are also involved in the production of immunoglobulin E (IgE) and are associated with lung functions such as forced expiratory volume (FEV). During normal pregnancy, women undergo significant changes in their gut and vaginal microbiome. The alpha diversity of microbiome dramatically decreases temporally during pregnancy with a reduction in the relative abundance of anti-inflammatory butyrate producing bacteria and an increase in pro-inflammatory phylum Proteobacteria, Bifidobacterium in the phylum Actinobacteria, and lactic acid-producing bacteria in preparation for energy demands of lactation. Such data are not available in the literature for women with asthma. The B-WELL-MOM (BWM) study is a prospective cohort study of 418 women with asthma and women with no asthma at two US sites that sought to understand factors that predict poor asthma control during pregnancy. Various measures of asthma severity, symptoms and medication were collected along with biospecimens from the first, second and third trimester of pregnancy and 4 months post-partum with accompanying infant samples at delivery and 4 mo. Microbiome samples were captured by collecting material into Epicentre Buccal Amp DNA extraction buffer and storing at -20.