Six years' experience in ovum donation using vitrified oocytes: report of cumulative outcomes, impact of storage time, and development of a predictive model for oocyte survival rate

Abstract

Objective: To describe the clinical outcomes achieved after 6 years' experience in ovum donation conducted with vitrified oocytes; to attempt to find predictors of survival; and to provide information about the probability of having a baby according to the number of oocytes consumed.

Design: Retrospective, observational study.

Setting: Private university-affiliated in vitro fertilization center.

Patient(s): Recipients of vitrified oocytes (January 2007-March 2013), including all the warming procedures (n = 3,610) and all the donations made during the same period (n = 3,467).

Intervention(s): None.

Main outcome measure(s): Survival rate per warming procedure, cumulative delivery rates (CDR) per single donation cycle, oocyte-to-baby rate, and cumulative live birth rate (CLBR) per oocyte consumed.

Result(s): Oocyte survival rate was 90.4%. It was not possible to develop a predictive model for survival owing to the lack of prognostic value of the studied variables. Implantation, clinical, and ongoing pregnancy rates per donation cycle were 39.0% (95% confidence interval [CI], 37.8-40.5), 48.4% (95% CI, 46.7-50.1), and 39.9% (95% CI, 38.3-41.5), respectively. Statistical differences were found when comparing blastocysts versus day 3 ETs (42.5%; 95% CI, 40.4-45.2 vs. 37.5%; 95% CI, 35.3-39.7 ongoing pregnancy rate). The CDR/donation cycle, including cryotransfers, was 78.8% (95% CI, 73.5-84.1). The oocyte-to-baby rate was 6.5%. CLBR increased progressively according to the number of oocytes consumed.

Conclusion(s): We provide detailed information about the high efficiency of using vitrified/warmed oocytes. There is currently no way of estimating donors' oocytes survival when considering baseline characteristics, storage time, or controlled ovarian stimulation parameters. The probability of achieving a baby using vitrified oocytes increases progressively with the number of oocytes consumed.

Keywords: Ovum donation; delivery rate; live birth; predictive value; survival rate; vitrification.