Association between residential ambient concentrations of air pollutants and fecundability, Snart Gravid and Snart Foraeldre, 2007–2019. Fecundability ratios are for a one-interquartile range increase in exposure, and are adjusted for age, education, income, parity conditional on gravidity, month of enrollment, year of enrollment, and average monthly ambient temperature. Models for NOx, NO2, CO and O3 are adjusted for PM2.5 and SO2. Models for PM2.5 and PM10 are adjusted for NOx and SO2. Models for SO2 are adjusted for NOx and PM2.5