The purpose of the Breathe – Wellbeing, Environment, Lifestyle and Lung Function Study (B-WELL Mom Study) is to examine the role of asthma control in pregnancy outcomes. This study examines poor asthma control in the context of the immunology of pregnancy and risk factors such as genetics, the environment, and social determinants of health. Women with and without asthma were recruited during the first trimester of pregnancy (< 15 weeks gestation) and followed through 4 months post-partum. Assessments occurred during each trimester of pregnancy (<15 weeks, 20-22 weeks, 30-32 weeks), at delivery, and 4 months post-partum. The B-WELL Mom study collected urine, microbiome swabs, and blood samples (PAXGene RNA, serum, plasma, and buffy coat) from approximately 400 subjects at each visit (<15 weeks, 20-22 weeks, 30-32 weeks) and 4 months post-partum. Nasal swabs were collected once during pregnancy, and placental tissue specimens and cord blood RNA were collected at delivery.