Objectives
We examined sexual orientation-related differences in various pregnancy outcomes (e.g., teen pregnancy, abortion) across the lifespan.

Methods
We collected data from 124,710 participants in three U.S. longitudinal cohort studies, the Nurses’ Health Study 2 and 3 and Growing Up Today Study 1, followed from 1989 to 2017. Multivariate regression was used to calculate differences of each outcome—ever had pregnancy, teen pregnancy, ever had abortion, and age at first birth—by sexual orientation groups (e.g., heterosexual, mostly heterosexual, bisexual, lesbian), adjusting for potential confounders of age and race/ethnicity.

Results
All sexual minority groups—except lesbians—were generally more likely than heterosexual peers to have a pregnancy, a teen pregnancy, and an abortion. For example, Growing Up Today Study 1 bisexual participants were three times as likely as heterosexuals to have had an abortion (risk ratio, 3.21; 95% confident interval, 1.94–5.34). Lesbian women in all of the cohorts were approximately half as likely to have a pregnancy compared with heterosexual women. Few sexual orientation group differences were detected in age at first birth.

Conclusions
The increased risk of unintended pregnancy among sexual minority women likely reflects structural barriers to sexual and reproductive health services. It is critical that sex education programs become inclusive of sexual minority individuals and medical education train health care providers to care for this population. Health care providers should not make harmful heteronormative assumptions about pregnant patients and providers must learn to take sexual histories as well as offer contraceptive counseling to all patients who want to prevent a pregnancy regardless of sexual orientation.