Monozygotic twins and triplets in association with blastocyst transfer.
OBJECTIVE
To compare the incidence of monozygotic twins following blastocyst versus day-3 embryo transfer (ET).


METHODS
A retrospective analysis of the outcome of assisted reproductive technology (ART) cycles utilizing blastocyst ET during 1999-2000 was compared to a similar group of patients undergoing day-3 ET during 1997-1998.


RESULTS
Blastocyst ET was used in 75 cycles with 2.0 +/- 2 embryos transferred. The comparison group consisted of 90 cycles with day-3 ET and 3.0 +/- 2 embryos transferred.


CONCLUSIONS
High pregnancy rates are maintained with blastocyst ET even though fewer embryos are transferred. The rate of monozygotic twins is higher with blastocyst ET than with day-3 ET. This increase may partially negate the benefit of reduced high-order multiple gestations attributed to blastocyst ET.
Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Southern California Keck School of Medicine, Los Angeles, California, USA.
John K
JK
Jain
Robert
R
Boostanfar
Cristin C
CC
Slater
Mary M
MM
Francis
Richard J
RJ
Paulson
D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D046149:Embryo Culture Techniques / Q000379:methods; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000502:physiology*; D012189:Retrospective Studies; D038522:Twinning, Monozygotic / Q000502:physiology*