Monozygotic pregnancies conceived by in vitro fertilization: understanding their prognosis.
OBJECTIVE
To analyze the outcomes and particular characteristics of monozygotic (MZ) pregnancies conceived by in vitro fertilization (IVF).


METHODS
Retrospective data analysis.


METHODS
Large private-academic fertility center.


METHODS
IVF-conceived MZ pregnancies.


METHODS
Statistical analysis of MZ pregnancy outcomes depending on fetal order and pregnancy reductions status.


METHODS
Spontaneous pregnancy reduction, pregnancy loss, take-home baby rate, perinatal mortality, gestational age at delivery, and birth weight.


RESULTS
A total of 72 of 3,426 pregnancies (2.1%) were MZ, and 70 were included in the study. Of these, 34 cases (48.5%) were high-order multiple pregnancies (HOMP), and 36 (51.5%) were non-HOMP. In the HOMP group, only 2.9% (1 of 34) had a complete pregnancy loss while 38.8% (14 of 36) of the non-HOMP were lost by 20 weeks' gestation. Of the HOMP patients, 73.1% therapeutically reduced the MZ component, and a statistically significant difference in gestational age of delivery (37.8 ± 3.2 vs. 28.1 ± 7.7) and birth weight (2796 ± 865.8 vs. 1110.0 ± 731.6) was seen when compared with nonreduced HOMP.


CONCLUSIONS
Twinning with MZ is encountered in a small but important number of pregnancies derived from assisted reproduction. The prognosis for these patients is unfavorable, particularly for single-implantation MZ pregnancies and for nonreduced HOMP. Patients who do not spontaneously reduce a MZ-HOMP by 12 weeks may benefit from therapeutically reducing the MZ component of the pregnancy.
Reproductive Medicine Associates of New York, New York, New York 10022, USA.
Gerardo
G
Vela
Martha
M
Luna
Jason
J
Barritt
Benjamin
B
Sandler
Alan B
AB
Copperman
D000328:Adult; D001724:Birth Weight / Q000502:physiology; D032882:Comprehension; D003944:Diagnostic Techniques, Obstetrical and Gynecological / Q000706:statistics & numerical data; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro / Q000379:methods / Q000706:statistics & numerical data*; D006801:Humans; D007246:Infertility / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D018607:Pregnancy Reduction, Multifetal / Q000706:statistics & numerical data; D011272:Pregnancy, Multiple / Q000502:physiology / Q000706:statistics & numerical data*; D011379:Prognosis; D012189:Retrospective Studies; D038522:Twinning, Monozygotic / Q000502:physiology*