OBJECTIVETo study the effect of patient age, the number and quality of embryo transferred on pregnancy outcome of in vitro fertilization-embryo transfer (IVF-ETs).

METHODSA retrospective study was performed in infertile women who underwent a total of 1800 cycles of IVF-ET and intracytoplasmic sperm injection (ICSI). The patients were divided into three age groups, namely<30 years group, 30-35 years group, and>or=35 years group. The clinical pregnancy rate and the multiple pregnancy rate were compared when 1, 2 or 3 embryos and 0, 1, 2 or 3 good-quality embryos were transferred.

RESULTSIn patients<30 years, no significant differences was found in the clinical pregnancy rate between 1, 2 and 3 embryos transfer groups; 2 and 3 good-quality embryos transfer resulted in similar pregnancy rate, which was significantly higher than that resulted from 0 and 1 good-quality embryo transfer. Multiple pregnancy was not found in 1 embryo transfer group. In patients aged 30-35 years, the pregnancy rate showed no significant differences not only between 1 and 2 embryos transfer groups, but also between 2 and 3 good-quality embryos transfer groups; multiple embryo transfer led to significantly increased multiple pregnancy rate. In patients aged>or=35 years, the transfer of 1, 2 and 3 embryos resulted in similar pregnancy rate; transfer of 3 good-quality embryos had obviously higher pregnancy rate than 0, 1 and 2 good-quality embryos transfer groups. Increased numbers of embryos and good-quality embryos transferred were both associated with increased multiple pregnancy rate.

CONCLUSIONOne good-quality embryo transfer in patients<30 years and 2 good-quality embryos transfer in patients>or=30 years can obtain ideal pregnancy rate and reduce the incidence of multiple pregnancy. For patients aged>or=35 years, transfer of only good-quality embryo is recommended.