Fig. 3
Smooth curves between the mean concentration of PM2.5 for each trimester and for the whole pregnancy and PROM*. *The orange line represents the association between the mean concentration of PM2.5 during the whole pregnancy and PROM, adjusted for year of birth, season of conception, maternal age, parity, maternal anemia, preeclampsia, gestational diabetes, and history of obstetrical-gynecological pathology (Model I); The purple line represents the association between the mean concentration of PM2.5 during the first trimester and PROM, adjusted for Model I plus mean concentration of PM2.5 in the second and third trimesters; The green line represents the association between the mean concentration of PM2.5 during the second trimester and PROM, adjusted for Model I plus mean concentration of PM2.5 in the first and third trimesters; The blue line represents the association between the mean concentration of PM2.5 during the third trimester and PROM, adjusted for Model I plus mean concentration of PM2.5 in the first and second trimesters