Air pollution had the strongest impact on the babies when the mothers were exposed during the second trimester. Surprisingly mothers that were exposed to high levels of air pollution during their third trimester resulted in the babies being born with longer telomeres to those whose mothers were exposed to less air pollution. It is not yet clear how these newborns would have benefitted from air pollution that would increase their telomeres. This study indicated that these newborns would age faster throughout their lifetime because of having shorter telomeres. A couple other factors to keep in mind are that air pollution could have not been the only leading cause of for the shortening of the babies telomeres, events such as stress, smoking, violence can have an impact on the baby's development.