Successful pregnancy outcome after cryopreservation of all fresh embryos with subsequent transfer into an unstimulated cycle.
OBJECTIVE
To assess the pregnancy outcome of freezing and storing all fresh embryos produced in a stimulated IVF cycle and replacing them in a subsequent nongonadotropin-stimulated cycle.


METHODS
Retrospective study.


METHODS
University-associated assisted reproductive technology program.


METHODS
We studied 36 patients (age range 23 to 44 years) who underwent cryopreservation of all fresh embryos in a controlled ovarian hyperstimulation (COH) cycle because of either the risk of severe ovarian hyperstimulation (24 patients, group 1) or the presence of an endometrial lining < 8 mm in thickness (12 patients, group 2). Five hundred fifty-five embryos were generated for replacement in 63 cycles. All embryos were cryopreserved in 1.5 M propanediol at the pronuclear or two-cell stage, and 264 embryos subsequently were transferred into a hormone replacement cycle (70%) or natural ovulatory cycle (30%). The average number of embryos transferred per patient was 4.2.


RESULTS
Twenty-one clinical pregnancies were achieved, giving a pregnancy rate (PR) of 58.3% per patient (33.3% per cycle). The live birth rate was 50% per patient (28.6% per cycle). The implantation rate was 9.1%. Groups 1 and 2 had a similar PR per patient (58.3%). With 208 cryopreserved embryos remaining and considering the 33.3% PR per cycle, we expect the overall extrapolated PR to be 63.9%.


CONCLUSIONS
This is the first series showing that freezing and storing all fresh embryos produced in a stimulated IVF cycle and replacing them in a subsequent nongonadotropin-stimulated cycle results in successful PRs. These results underlie the importance of a successful cryopreservation program in IVF and could be a possible approach to overcoming the alleged adverse effects of COH on the endometrium, thereby improving the chances of pregnancy when numerous embryos are obtained simultaneously.
Frederick
J L
JL
Department of Obstetrics and Gynecology, University of California, Irvine, Orange 92613-1491, USA.
Ord
T
T
Kettel
L M
LM
Stone
S C
SC
Balmaceda
J P
JP
Asch
R H
RH
D000328:Adult; D015925:Cryopreservation / Q000592:standards*; D004624:Embryo Transfer / Q000379:methods / Q000592:standards*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D008297:Male; D010060:Ovulation / Q000502:physiology*; D010062:Ovulation Induction; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D012189:Retrospective Studies