This study takes a lifecourse approach to understanding the factors contributing to delivery methods in the US by identifying preconception and pregnancy-related determinants of medically indicated and non-medically indicated cesarean section (C-section) deliveries. Data are from the Early Childhood Longitudinal Study-Birth Cohort, a nationally representative, population-based survey of women delivering a live baby in 2001 (n = 9,350). Three delivery methods were examined: (1) vaginal delivery (reference); (2) medically indicated C-section; and (3) non-medically indicated C-sections. Using multinomial logistic regression, we examined the role of sociodemographics, health, healthcare, stressful life events, pregnancy complications, and history of C-section on the odds of medically indicated and non-medically indicated C-sections, compared to vaginal delivery. 74.2 % of women had a vaginal delivery, 11.6 % had a non-medically indicated C-section, and 14.2 % had a medically indicated C-section. Multivariable analyses revealed that prior C-section was the strongest predictor of both medically indicated and non-medically indicated C-sections. However, we found salient differences between the risk factors for indicated and non-indicated C-sections. Surgical deliveries continue to occur at a high rate in the US despite evidence that they increase the risk for morbidity and mortality among women and their children. Reducing the number of non-medically indicated C-sections is warranted to lower the short- and long-term risks for deleterious health outcomes for women and their babies across the lifecourse. Healthcare providers should address the risk factors for medically indicated C-sections to optimize low-risk delivery methods and improve the survival, health, and well-being of children and their mothers.