Individualized Prolonged Luteal Support After Fresh Embryo Transfer in Women With Low Progesterone

The goal of this clinical trial is to compare live birth rate in a control group versus an interventional group in subjects aged 18 to 37, pregnant after a fresh embryo transfer and with a serum progesterone level below 17 ng/mL on the day of pregnancy test while using vaginal progesterone as a luteal support. . This is the first randomized controlled trial to assess the benefit of prolonged subcutaneous progesterone administration in patients with a positive pregnancy test (Bêta chorionique gonadotropic hormone: β-hCG \>100 IU/L) after fresh transfer and low progesterone level (\<17 ng/mL). Half the participants will be offered a an extension of luteal phase support , by subcutaneous progesterone supplementation for 6 weeks, the other half will have placebo injections. A double-blind, placebo-controlled, randomized design was chosen to prevent selection bias and ensure the comparability of both study arms.