Factors affecting pregnancy rates of in vitro fertilization and gamete intrafallopian transfer.

Factors affecting pregnancy rates in gamete intrafallopian transfer (GIFT) and in vitro fertilization (IVF) were evaluated. Higher pregnancy rates were found when more mature oocytes were recovered (6.2 +/- 2.5 vs 3.8 +/- 3.0) and more oocytes (4.6 +/- 1.0 vs 3.3 +/- 1.2) or zygotes (4.7 +/- 1.4 vs 3.0 +/- 1.7) were transferred. Ultrasound-guided follicular aspiration was successful for in vitro fertilization and had a pregnancy rate (14.3%) comparable to the laparoscopic approach (13.3%). Laparotomy for correction of pelvic pathology concomitant with oocyte retrieval should be used cautiously despite the high preliminary pregnancy rate (42.9%). Failed fertilization of the surplus oocytes left after gamete intrafallopian transfer did not mean a poor chance of pregnancy (27.6%). The combined treatment of gamete intrafallopian transfer and in vitro fertilization may have a higher chance of pregnancy (43.5% vs 21.4% in GIFT and 13.3% in IVF), and more multiple pregnancies (40.0% vs 22.2% in GIFT and 16.7% in IVF). Cycles with spontaneous LH (luteinizing hormone) surges, detected by daily morning urine samplings, need not be aborted and the timing of ovum recovery should be individually evaluated.