A sensitivity analysis in which preterm births (n = 14 for total group; n = 12 for 3-NTp group), mothers with gestational diabetes/hypertension (n = 20 for total group; n = 19 for 3-NTp group), and mothers with preeclampsia (n = 2 for both groups) were excluded showed very little change in the estimated associations between the overall placental methylation of the LEP promoter region and second-trimester PM2.5 exposure or placental 3-NTp content (see Table S3). Here, LEP is linked to preeclampsia.