Discussions surrounding surgical approach and minimizing complications and perioperative risks are necessary for many surgeries. Obesity introduces additional variables and risks that need to be discussed in making decisions about pelvic reconstructive surgery, particularly because it is associated with comorbidities such as diabetes, cardiovascular disease, chronic kidney disease, and others. Medical and surgical risks also increase proportionally to the severity of obesity. Previous studies have investigated associations between body mass index (BMI) and individual surgical approaches, but there is a lack of research assessing comparisons between surgical approaches in cohorts of normal BMI versus elevated BMI. This study was designed to assess differences in complications for pelvic organ prolapse surgery by BMI category and surgical approach, with secondary outcomes of prolonged length of stay, unplanned readmission, and unplanned reoperation. This was a retrospective cohort study with data obtained from the American College of Surgeons National Surgical Quality Improvement Program electronic database, which contains 1,020,511 surgical cases from 722 hospitals. Inclusion criteria were women aged 18 to 89 years, who underwent vaginal or laparoscopic surgery for pelvic organ prolapse between 2007 and 2018. Exclusion criteria were concomitant hysterectomy via an open abdominal route, emergency operation, BMI less than 18.5 kg/m2, and missing height or weight information. Final analysis included 26,940 women who had prolapse procedures, with 25,933 having a BMI less than 40 and 1007 having a BMI of 40 kg/m(2) or greater. Vaginal procedures were performed more frequently overall, as well as more frequently among those in the lower BMI group. Individuals with a higher BMI were more likely to have diabetes, hypertension requiring pharmacotherapy, and severe chronic obstructive pulmonary disease; however, the rates of concomitant hysterectomy or anti- incontinence procedures were not significantly different between groups. The proportion of major complications was significantly higher in the women with a higher BMI (2.0% vs 1.1%, P = 0.007), with 1.8 times increased risk (95% confidence interval, 1.1-2.9; P = 0.04). This was largely affected by surgical approach; there was no significant increase in risk for major complication for vaginal prolapse repair, but there was a 6-fold greater risk of major complication for individuals with a BMI of 40 kg/m2 or greater undergoing a laparoscopic prolapse repair (adjusted odds ratio, 6.0; 95% confidence interval, 2.5-14.6; P < 0.001). These results show that the risk of major complication from pelvic organ prolapse surgery was significantly increased in women with a BMI of 40 kg/m(2) or greater. This is consistent with previous literature indicating that a higher BMI increases the risk of morbidity in general and is important to consider in the context of rising BMI in the United States. These findings should impact patient preoperative counseling and inform decisions about surgical approach. Future research should focus on removing potential confounders and gathering additional data about factors that were unavailable in the database, such as surgeon volume, socioeconomic status, hospital type, robotic experience, and regional BMI trends.