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.
Jain
John K
JK
Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Southern California Keck School of Medicine, Los Angeles, California, USA.
Boostanfar
Robert
R
Slater
Cristin C
CC
Francis
Mary M
MM
Paulson
Richard J
RJ
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*