ABSTRACT: To examine whether a first abortion increases risk of mental health disorders compared with a first childbirth with and without considering prepregnancy mental health and adverse exposures, childhood economic status, miscarriage history, age at first abortion or childbirth, and race or ethnicity.A cohort study compared rates of mental disorders (anxiety, mood, impulse-control, substance use, eating disorders, and suicidal ideation) among 259 women postabortion and 677 women postchildbirth aged 18-42 years at the time of interview from The National Comorbidity Survey-Replication.The percentage of women with no, one, two, and three or more mental health disorders before their first abortion was 37.8%, 19.7%, 15.2%, and 27.3% and before their first childbirth was 57.9%, 19.6%, 9.2%, and 13.3%, respectively, indicating that women in the abortion group had more prior mental health disorders than women in the childbirth group (P<.001). Although in unadjusted Cox proportional hazard models, abortion compared with childbirth was associated with statistically significant higher hazards of postpregnancy mental health disorders, associations were reduced and became nonstatistically significant for five disorders after adjusting for the aforementioned factors. Hazard ratios and associated 95% confidence intervals dropped from 1.52 (1.08-2.15) to 1.12 (0.87-1.46) for anxiety disorders; from 1.56 (1.23-1.98) to 1.18 (0.88-1.56) for mood disorders; from 1.62 (1.02-2.57) to 1.10 (0.75-1.62) for impulse-control disorders; from 2.53 (1.09-5.86) to 1.82 (0.63-5.25) for eating disorders; and from 1.62 (1.09-2.40) to 1.25 (0.88-1.78) for suicidal ideation. Only the relationship between abortion and substance use disorders remained statistically significant, although the hazard ratio dropped from 3.05 (1.94-4.79) to 2.30 (1.35-3.92).After accounting for confounding factors, abortion was not a statistically significant predictor of subsequent anxiety, mood, impulse-control, and eating disorders or suicidal ideation. LEVEL OF EVEDIENCE: II.