Panneerselvam, P.; K., Y.; Prakash, S.; Sritharan, M.; Elanchezhian, M. A Retrospective Cohort Study on Optimal Serum Progesterone Levels before FET Cycles Using Vaginal and Parenteral Progesterone Supplementation and Its Pregnancy Outcomes. Int J Reprod Contracept Obstet Gynecol 2025, 14, 2544-2551.