Navi Khan, Gul Ar, Nazia Ishrat, and Zulquarnain . “Analysis of Heart Rate Variability in Pre-Eclamptic Pregnancy: A Study Employing Frequency Domain Analysis”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology 3, no. 4 (February 10, 2017): 1037–1042. Accessed December 4, 2025. https://www.ijrcog.org/index.php/ijrcog/article/view/2223.