During the follow-up phase female partner receives supplemental progesterone to maintain integrity of the uterine lining. Progesterone may be administered by a vaginal gel preparation, Intramuscular injection or vaginal suppository.  After 10-12 days of embryo transfer, serum ßhCG is measured to predict blood test is done to predict possible pregnancy. Rising blood levels of pregnancy hormone (ßhCG) , indicate that implantation has occurred. Affirmation of a clinical pregnancy is made by ultrasound examination four weeks following the transfer.