We investigated sexual orientation disparities in several obstetric and perinatal outcomes in Louisiana and examined whether these disparities differed among Black, Latine, and White populations. We analyzed cross-sectional vital records data on singleton live births in Louisiana (2016-2022). Same-sex relationships (SSR) vs. different-sex relationships (DSR) were classified based on the sex of the parents listed on the birth certificate. Using modified Poisson regression, we estimated adjusted risk ratios and 95% confidence intervals among birthing persons in SSR vs. DSR for preterm birth (PTB), low birthweight (LBW), spontaneous labor, Cesarean delivery, gestational hypertension, and gestational diabetes. We examined within and across group disparities in models stratified by sexual orientation and race/ethnicity. In the total birthing population, those in SSR experienced higher risk of gestational hypertension and gestational diabetes and were less likely to have spontaneous labor compared with persons in DSR. The risk of PTB and LBW was two-fold higher among Black birthing people in SSR compared with White birthing people in SSR and DSR. Latine birthing people in SSR experienced higher risk of gestational hypertension and gestational diabetes compared with their peers in DSR and White people in DSR. Some of these disparities were partially explained by including socioeconomic and health risk factors. Sexual orientation-related disparities exist across and within racial/ethnic groups among birthing people in Louisiana. Adopting an intersectional approach that considers the mutually constituted nature of heterosexism and racism is critical to addressing sexual orientation-related inequities in reproductive and perinatal health.