Day 2 transfer improves pregnancy outcome in in vitro fertilization cycles with few available embryos.

Objective: Delaying ET to day 3 to optimize embryo selection is well accepted. However, in cases where there are not enough embryos to perform selection, it is not clear whether there is a difference in clinical outcomes with the day of ET.
Design: Cohort study.
Setting: Academic medical center.
Patient(s): Two hundred forty-two fresh IVF/intracytoplasmic sperm injection (ICSI) cycles from 2002-2004, where all generated embryos were transferred irrespective of quality because of an extremely low number of available embryos.
Intervention(s): In time period 1, ET was on day 3. In time period 2, ET was on day 2.
Main Outcome Measure(s): Patient response to stimulation was analyzed along with pregnancy outcome and implantation rate.
Result(s): Miscarriage rates were decreased, and ongoing pregnancy rates were increased with a day 2 ET in patients <40 years of age.
Conclusion(s): In women <40 years of age, the day of transfer is a significant predictor of clinical outcome in cases in which a low number of embryos are available for transfer. The evidence suggests that limiting embryo culture to only 2 days reduces the incidence of miscarriage and increases ongoing pregnancy rates.