Perinatal outcomes after fresh versus vitrified-warmed blastocyst transfer: retrospective analysis.

OBJECTIVE

To investigate the possible effect of controlled ovarian stimulation on the perinatal outcomes of assisted reproductive technology pregnancies, by comparing the outcomes from fresh ET with frozen ET (FET) with blastocysts of similar quality.

DESIGN

Retrospective observational study.

SETTING

Private fertility center.

PATIENT(S): Seven hundred eighty-four fresh transfers and 382 vitrified-warmed double blastocyst transfers.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Miscarriage, perinatal mortality, preterm delivery, live birth, live-birth weights, and gestational age of live births.

RESULT(S): FET resulted in higher implantation rates (51.5% vs. 40.6%), higher live-birth rates per transfer (56.8% vs. 44.3%), and lower ectopic pregnancy rates (0.32% vs. 1.80%). FET pregnancies also had higher day 14 βhCG levels per implantation (148.2 vs. 176.2 IU/L) and higher infant birth weights (singletons Δ109.4 g, twins Δ124 g). Female infants benefitted the most in terms of birth weight. Miscarriage, premature delivery, perinatal morbidity, and live birth per pregnancy were all nonsignificantly different between fresh ET and FET.

CONCLUSION(S): Clinically significant differences between the peri-implantation and perinatal outcomes of fresh ET and FET suggest better endometrial receptivity and placentation in FET cycles.