['We sought to assess the fertilization, implantation, and ongoing pregnancy rates with a minimal precycle and ongoing cycle monitoring protocol for in vitro fertilization and embryo transfer.', 'Retrospective review was conducted of 103 consecutive cycles of fresh in vitro fertilization and embryo transfer from 1996 to 1998. Precycle screening included semen analysis without strict morphologic analysis, and hysterosalpingography-sonohysterography within the last year. Serum prolactin, serum thyroid-stimulating hormone, reactive plasma reagin, human immunodeficiency virus, rubella titer, blood type, hepatitis B surface antigen, and hepatitis C antibody testing was performed on all patients within 3 months of cycle initiation. Women > or =37 years old underwent clomiphene challenge testing. The monitoring protocol included the following: baseline transvaginal ultrasonography after 12 to 14 days of midluteal gonadotropin-releasing hormone agonist down-regulation to assess endometrial thickness and adnexal appearance, transvaginal ultrasonography for follicle evaluation at 7 and 10 days, serum estradiol assay if > or =20 follicles, quantitative beta-human chorionic gonadotropin 12 to 14 days after pre-embryo transfer, repeat quantitative beta-human chorionic gonadotropin 3 to 5 days later, and transvaginal ultrasonography for intrauterine gestational sac confirmation 7 to 9 days after the initial positive pregnancy test result. The dose of gonadotropin used remained constant unless the sonogram obtained on day 7 indicated a suboptimal response (<3 follicles each, with an average diameter of 10 to 12 mm) or hyperresponse (> or =15 follicles with an average diameter of 10 to 12 mm).', 'The per embryo implantation rate (fetal cardiac activity) was 13.1%, and the live birth rate per 100 pre-embryo transfers was 31.5 for patients < or =40 years old. The average number of pre-embryos transferred was 3.1. The singleton pregnancy rate was 71%, and there were no multiple gestations greater than twins. The mean number of oocytes fertilized was 66%. There was 1 case of failed fertilization with intracytoplasmic sperm injection. There were two other cases of failed fertilization. One case of severe ovarian hyperstimulation occurred in spite of cryopreservation of all embryos.'] Do minimal precycle testing and ongoing cycle monitoring for in vitro fertilization and fresh pre-embryo transfer compromise fertilization , implantation , or ongoing pregnancy rates?