Abstract: Objective：To investigate the effect of female age on the pregnancy outcomes, as well as ovarian responses, of in vitro fertilization-embryo transfer（IVF -ET）, and to find the optimal age range for women undergoing the associated reproduction treatments. Methods: This is a retrospective analysis of all patients firstly undergoing IVF -ET using the standard long protocol for the controlled ovarian hyperstimulation（COH） in our center from May 2011 to May 2012. Patients were divided into four groups according to female age: age of the group A was 20-24 years old（n=170）, the group B 25-29 years old（n=741）, the group C 30-34 years old（n=866）, and the group D over 35 years old（n=691）. The laboratory indexes and main clinical outcomes [pregnancy rate, miscarriage rate and live birth rate（LBR）] were compared. Results：The duration of infertility was significantly longer following female age. The basal FSH level of the group D was significantly higher than those of other groups, while AFC and the basal LH level were significantly lower following age. The mean total dose of Gn was increased following age, while the number of mean retrieved oocyte was decreased. The 2PN zygote rate in group A was significantly lowest. The high quality embryo rate was significantly higher in the group B than this in other groups. The biochemical pregnancy rate and LBR were significantly lowered following age, while the spontaneous abortion rate was increased following age. The clinical pregnancy rate of group B is significantly higher than group D. LBR in the group D was significantly lower, and the spontaneous abortion rate was higher when compared with other groups. Conclusions: The oocyte quality and embryo quality in those women aged <25 years undergoing ART are not better than those in women aged 25-29 years, while the pregnancy rates in two groups are similar. The ovarian reserve, and pregnancy outcome of IVF-ET, will reduce following age, especially in those women aged over 35 years.

Key words: Fertilization in vitro, Embryo transfer, Superovulation, Age factors, Pregnancy outcome