Effect of aging on the female reproductive system: evidence for a role of uterine senescence in the decline in female fecundity.

OBJECTIVE

To determine the effects of age on reproductive performance of women using oocyte donation as an in vivo model.

SETTING

Oocyte donation and IVF programs at the Instituto Valenciano de Infertilidad.

PATIENTS

Seventy-six women undergoing 90 cycles of ovum donation, who were recipients of 36 donors undergoing IVF, and 9 fertile women.

DESIGN

Prospective longitudinal study: [1] recipients underwent an artificial cycle to demonstrate adequate response of the endometrium to exogenous steroids; [2] oocytes from the same cohort of follicles were distributed randomly into recipients younger and older than 40 years; and [3] pregnancies were followed during the first trimester.

MAIN OUTCOME MEASURES

Endometrial histology, fertilization, embryo quality, pregnancy, implantation, and abortion rates in both groups of recipients. Serum E2, P and beta-hCG levels during initial pregnancy.

RESULTS

Similar implantation rates but significantly higher abortion rates were detected in women > 40 years despite an appropriate action of P on the endometrium and the transfer of embryos in similar number and quality. The secretion of E2 and P by the placenta started earlier in pregnancies included in the group < 40 years.

CONCLUSIONS

Age increases pregnancy losses in ovum donation patients after implantation is completed. This is accompanied by a retardation of steroid synthesis and suggests that the mechanism(s) responsible for placenta formation and functioning in the uterus is affected by age. Thus, uterine aging also is a factor influencing the poor reproductive performance of women with advancing age.