Day 4 versus day 3 embryo transfer: a prospective study of clinical outcomes.

OBJECTIVE

To compare the clinical outcomes after day 4 or day 3 embryo transfers in controlled ovarian hyperstimulation-IVF/intracytoplasmic sperm injection (ICSI) cycles.

DESIGN

Prospective randomized study.

SETTING

Center for Human Reproduction, 'Genesis Athens' Clinic (private gynecological and surgical clinic), Athens, Greece.

PATIENT(S): Three hundred fifty women with primary infertility and indication for IVF/ICSI treatment. Patients were randomly allocated to day 4 or day 3 embryo transfer.

INTERVENTION(S): Controlled ovarian hyperstimulation, oocyte retrieval, IVF/ICSI, embryo transfer.

MAIN OUTCOME MEASURE(S): Implantation rate; clinical, ongoing, and multiple pregnancy rates.

RESULT(S): A trend toward higher clinical and ongoing pregnancy rates was noted after day 4 embryo transfers. Implantation and multiple pregnancy rates were comparable after day 4 or day 3 embryo transfers.

CONCLUSION(S): The transfer of day 4 embryos in IVF/ICSI cycles may result in favorable implantation and pregnancy rates which are at least comparable to those after the transfer of day 3 embryos.