D., Muthulakshmi, Sasirekha R., and Medha R. “Serum β-Hcg Levels Between 12 to 20 Weeks of Gestation in Prediction of Hypertensive Disordrers of Pregnancy”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology 6, no. 8 (July 26, 2017): 3347–3351. Accessed December 29, 2025. https://www.ijrcog.org/index.php/ijrcog/article/view/3363.