Is there increased monozygotic twinning after assisted reproductive technology?

Abstract

Over the past two decades there has been an association between assisted reproductive technologies and increased monozygotic twinning. The association is not clear nor are the causes of assisted reproductive technology-related monozygotic twinning understood, although there are several theories as to the possible mechanisms involved. This review looks at some of the assisted reproductive technologies which may be associated with an increased risk of monozygotic twinning such as intracytoplasmic sperm injection, assisted hatching and blastocyst transfers. Determining the true incidence of monozygotic twinning after assisted reproductive technologies is important as there is a well-documented increase in perinatal morbidity and mortality of monozygotic twins compared to singleton and dizygotic pregnancies.

Monozygotic twinning associated with assisted reproductive technologies: a review

“…The only association with temperature changes and MZ twinning that have been addressed is the incidence of MZ twinning following the transfer of frozen-thawed embryos. There has been brief mention of the potential for such an association (Toledo 2005, Faraj et al 2007), but other reports indicate no relationship between the transfer of frozen-thawed embryos and MZ twinning rate (Alikani et al 2003, Blickstein et al 2003. If embryo cryopreservation results in increased MZ twinning, the increase is likely associated with zona hardening rather than a direct temperature effect.…”

Monozygotic twins with discordant karyotypes following preimplantation genetic screening and single embryo transfer: case report

“…Numerous articles have reported a significantly higher incidence of MZT following assisted reproduction cycles than after natural conception [1,[3][4][5][6][7][8].…”

“…There is an increased incidence of fetal growth restriction, fetal loss, pre-term delivery and perinatal loss [5,7]. MZT with monochorionic placentation are often complicated by feto-fetal transfusion syndrome and also play a role in the etiology of cerebral palsy, and pathogenesis of congenital abnormalities such as cardiac and brain anomalies or other clinical syndromes [9].…”

High incidence of monozygotic twinning in infertility treatment

“…multiple pregnancies incur a higher risk of perinatal morbidity, mortality, prematurity, and growth restrictions. mZT pregnancies are associated with a perinatal mortality rate at least three-fold higher than that associated with dizygotic twin pregnancies 34 , and the twins are also at greater risk of perinatal morbidity associated with prematurity than are dizygotic twins. They display higher rates of fetal abnormalities, including neural-tube defects, congenital heart diseases, limb reduction defects, and deformities.…”