Ja. Schnorr et al., Impact of a cryopreservation program on the multiple pregnancy rate associated with assisted reproductive technologies, FERT STERIL, 75(1), 2001, pp. 147-151
Objective: To determine the impact of a cryopreservation program on pregnan
cy rates and multiple-pregnancy rates in ART cycles.
Design: Retrospective study.
Setting: University teaching hospital.
Patient(s): Women who underwent stimulation for in vitro fertilization at t
he Jones Institute for Reproductive Medicine between October 1987 and June
1999.
Intervention(s): Analysis of pregnancy and multiple-pregnancy rates based o
n the number of embryos transferred.
Main Outcome Measure(s): Implantation; pregnancy and multiple-pregnancy rat
es.
Result(s): Pregnancy rates per transfer increased from 9% when one embryo w
as transferred to 20% with two embryos, 35% with three embryos, 40% with fo
ur embryos, and 41% with five embryos. The rate of twin pregnancies increas
ed to 21% with two embryos, 23% with three embryos, 21% with four embryos,
and 22% with five embryos. The triplet pregnancy rates were 8% with three e
mbryos, 9% with four embryos, and 2% with five embryos. A theoretical model
limiting the number of embryos transferred to two with cryopreservation an
d subsequent transfer yields a cumulative pregnancy rate of 77%, a twin rat
e of less than 20%, and no triplet or higher-order pregnancies.
Conclusion(s): The use of a cryopreservation program can help maximize preg
nancy rates while minimizing multiple-pregnancy rates. Cryopreservation sho
uld be considered in all assisted reproductive technology cycles. (C) 2001
by American Society for Reproductive Medicine.