Ovum pick-up was performed 32 to 36 hours after hCG administration by vaginal US and ET 48 hours later. Hydrogenized P vaginal suppositories, 50 mg., two times per day (privately manufactured by separation of the chemical compound into small micrometer-size particles providing optimal absorption and maximal levels of biologically active P) were given throughout the luteal phase and were continued until a pregnancy test was negative or up to the 7th week of pregnancy.