Raheja, Aastha, Krishna Agarwal, Rini Pachori, and Gauri Gandhi. “Tramadol Versus Placebo for Labor Analgesia in Low Risk Women: A Randomized Controlled Trial”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology 9, no. 1 (December 26, 2019): 342–347. Accessed December 4, 2025. https://www.ijrcog.org/index.php/ijrcog/article/view/7658.