ABSTRACT
Developments in assisted reproductive technology have allowed us to decrease the numbers of transferred embryos and thereby reduce the risk of multifetal pregnancies. However, even when the numbers of transferred embryos are restricted, the incidence of monozygotic multiple pregnancies is not reduced, and can be significantly higher than normal. We report two cases of monochorionic triamniotic triplet pregnancies after applying assisted reproductive technology. Three male babies were born in one pregnancy and the other pregnancy aborted at 10 weeks of gestation. Several factors, such as manipulation of the zona pellucida or extended blastocyst culture, might increase the risk of such monozygotic multiple gestations in this setting, but the actual causes remain unknown. Besides detecting predictive factors for monozygotic pregnancies, any manipulation of the zona pellucida in combination with blastocyst culture must be done cautiously to minimize the likelihood of monochorionic multiple pregnancies.
