Pregnancy / Progesterone / Humans / Fertility and Sterility / Female / In Vitro Fertilization / Pregnancy Loss / Embryo Transfer / Clinical Sciences / Gels / Public health systems and services research / Fertilization in Vitro / Pregnancy Rate / Pregnancy Outcome / Corpus Luteum / In Vitro Fertilization / Pregnancy Loss / Embryo Transfer / Clinical Sciences / Gels / Public health systems and services research / Fertilization in Vitro / Pregnancy Rate / Pregnancy Outcome / Corpus Luteum