Influence of patient age on the growth and transfer of blastocyst-stage embryos

To examine the effects of patient age on the growth and transfer of blastocyst-stage embryos.

Retrospective clinical study.

Private assisted reproductive technologies center.

Three hundred patients between the ages of 18 and 45 undergoing in vitro fertilization.

Bipronucleate oocytes were grown for up to 144 hours and subsequently transferred when at least one embryo attained the expanded blastocyst stage.

Oocytes retrieved and fertilized, blastocyst formation rates, implantation rates, and pregnancy rates per retrieval and transfer.

The rate of cycle cancellation before oocyte retrieval increased significantly with age, and the average number of oocytes per retrieval declined significantly with age. Fertilization rates were unrelated to patient age. The proportion of cycles with expanded blastocysts declined significantly with age. Pregnancy rates per stimulation declined with age, but pregnancy rates per transfer were approximately 50% across the entire age range studied.

The decline in female fertility with age appears to be the result of reduced numbers of oocytes and the inability of fertilized oocytes to develop to the blastocyst stage. Implantation and pregnancy rates appear to be unaffected by age when blastocysts do form.