The goal of this observational study is to compare two commonly used vaginal progesterone formulations - soft capsules versus pessaries - in women undergoing frozen embryo transfer (FET). The main question it aims to answer is:
\- Do soft vaginal progesterone capsules provide similar or better patient satisfaction, convenience, and tolerability compared with vaginal progesterone pessaries during preparation for frozen embryo transfer?
Participants undergoing FET who are prescribed vaginal progesterone as part of their endometrial preparation and luteal phase support will use one of the two formulations and complete patient-reported assessments regarding satisfaction, convenience, and tolerability. The study will also measure serum progesterone levels on the day of embryo transfer and evaluate pregnancy outcomes, including clinical pregnancy and live birth rates.