Maslowsky J, Stritzel H, Al-Hamoodah L, et al. - The national United States population of first-time and repeat teenage mothers were compared regarding the prevalence of negative pregnancy-related behaviors and gestational health conditions. Annual US birth data files from 2015 to 2018, N = 799,756 (673,394 [84.2%] first, 126,362 [15.8%] repeat) births to women ages 15-19 years, were used to perform this retrospective, population-based cohort study. Per findings, repeat teenage mothers had lower prevalence of physical health complications (gestational hypertension and gestational diabetes) during pregnancy but greater engagement in negative pregnancy-related health behaviors (inadequate prenatal care, smoking, inadequate weight gain, and sexually transmitted infection during pregnancy; they were also less likely to breastfeed). Direct correlation of negative health behavior in pregnancy is observed with poor perinatal outcomes for infants. Adverse outcomes from repeat teenage childbearing may reduce with ensuring access to quality, timely, prenatal and postpartum care so teenage mothers can receive support for healthy pregnancy-related behaviors, as well as with linkage to highly effective contraception to prevent unintended repeat births.