Increased risk of monochorionic twinning associated with assisted reproduction.
OBJECTIVE
To determine the incidence of monochorionic twinning in pregnancies resulting from assisted reproduction technologies (ARTs).


METHODS
We reviewed our experience with 218 ART pregnancies achieved over 3 years. All patients underwent transvaginal ultrasound 26 and 36 days after oocyte retrieval. The presence of two yolk sacs or two fetal poles within one sac suggested monochorionicity, and was confirmed by follow-up ultrasound and placental pathology. The various ARTs were compared to determine if any method had an increased incidence of monochorionicity compared to any other method. Statistical analysis was performed employing Chi Square analysis.


RESULTS
The incidence of monochorionicity in all gestations was 3.2% (8 times background rate); among multiple gestations it was 9.8%. The rates of monochorionicity for each ART appeared similar.


CONCLUSIONS
The incidence of monochorionic twinning is increased in pregnancies resulting from ART. Careful ultrasound evaluation of such pregnancies for monochorionicity is strongly recommended, both for planning of prenatal care and when considering a multifetal pregnancy reduction procedure.
Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, Iowa City.
K D
KD
Wenstrom
C H
CH
Syrop
D G
DG
Hammitt
B J
BJ
Van Voorhis
D002823:Chorion / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012099:Reproductive Techniques / Q000009:adverse effects*; D012307:Risk Factors; D014430:Twins, Monozygotic; D014463:Ultrasonography