Blastocyst-stage embryo transfer in patients who failed to conceive in three or more day 2-3 embryo transfer cycles: a prospective, randomized study.

Objective: To compare blastocyst-stage embryo transfers (ETs) with day 2-3 ETs in patients who failed to conceive in three or more day 2-3 IVF/ET cycles.

Design: Prospective, randomized.

Setting: Fertility unit in a university medical center.