The exogenous progesterone-free luteal phase: two pilot randomized controlled trials in IVF patients. - Humaidan, Peter; Alsbjerg, Birgit; Elbaek, Helle Olesen; Povlsen, Betina Boel; Laursen, Rita Jakubcionyte; Jensen, Mette Brix; Mikkelsen, Alice Toft; Thomsen, Lise Haaber; Kol, Shahar; Haahr, Thor (Reproductive BioMedicine Online (Elsevier Science), 2021)