Background: We monitored exposure to fine particulates (PM2.5), ozone, nitrogen dioxide (NO2), and ambient temperature for pregnant women with and without asthma.Methods: Women (n= 40) from the Breathe-Well-Being, Environment, Lifestyle, and Lung Function Study (2015-2018) were enrolled during pregnancy and monitored for 2-4 days. Daily pollutants were measured using personal air monitors, indoor air monitors, and nearest Environmental Protection Agency's stationary monitors based on GPS tracking and home address.Results: Personal-monitor measurements of PM2.5, ozone, and NO(2)did not vary by asthma status but exposure profiles significantly differed by assessment methods. EPA stationary monitor-based methods appeared to underestimate PM2.5 and temperature exposure and overestimate ozone and NO(2)exposure. Higher indoor-monitored PM2.5 exposures were associated with smoking and the use of gas appliances. The proportion of waking-time during which personal monitors were worn was similar to 56%. Lower compliance was associated with exercise, smoking, being around a smoker, and the use of a prescription drug.Conclusions: Exposure did not vary by asthma status but was influenced by daily activities and assessment methods. Personal monitors may better capture exposures but non-compliance merits attention. Meanwhile, larger monitoring studies are warranted to further understand exposure profiles and the health effects of air pollution during pregnancy.