Day 3 embryo transfer with combined evaluation at the pronuclear and cleavage stages compares favourably with day 5 blastocyst transfer

Rienzi, Laura
Ubaldi, Filippo
Iacobelli, Marcello
Ferrero, Susanna
Minasi, Maria Giulia
Martinez, Francisco
Tesarik, Jan
Greco, Ermanno

¹Reproductive Medicine, European Hospital, Via Portuense 700, 00149 Rome, Italy and ²MAR&Gen, Molecular Assisted Reproduction and Genetics, Gracia 36, 18002 Granada, Spain

³To whom correspondence should be addressed. E-mail: [email protected]

Submitted on January 9, 2002; accepted on March 3, 2002

Human Reproduction 17(7):p 1852-1855, July 2002.

BACKGROUND:

The respective advantages of day 3 and day 5 embryo transfer are a matter of debate. Previous comparisons did not include pronuclear stage zygote scoring and cumulative success rates (fresh and cryopreserved embryos).

METHODS:

Patients were randomized prospectively for day 3 or day 5 embryo transfer. Day 3 embryos were selected for transfer and cryopreservation by using combined evaluation at the pronuclear and cleavage stages.

RESULTS:

There was no difference between day 3 and day 5 fresh embryo transfers as to the rates of pregnancy (58 versus 62%), clinical pregnancy (56 versus 58%), delivery (50 versus 48%), implantation (35 versus 38%) and birth (33 versus 36%) rates. The corresponding values for cryopreserved embryo transfers were also similar. However, day 3 embryo transfer compared favourably with day 5 transfer when the pregnancy (90 versus 66%), clinical pregnancy (85 versus 62%) and delivery (77 versus 52%) rates were calculated per oocyte recovery attempt.

CONCLUSIONS:

With a selected population of good prognosis patients and our embryo selection criteria, the implantation potential of day 3 and day 5 embryos is equal. Per oocyte recovery attempt, day 3 transfer is more clinically efficient than day 5 transfer, but at least one transfer of cryopreserved embryos is necessary to manifest this superiority.