A normal baby is possible despite twins following a single embryo transfer even if one twin is genetically defective

To demonstrate that it is important to consider all possibilities when confronted with a decision to terminate a pregnancy because it is likely to be chromosomally abnormal.

A cell free DNA test was performed on a woman with dichorionic diamniotic twins that followed the transfer of a single embryo.

The cell free DNA test was consistent with trisomy 21. Two perinatologists favored identical twins and thus suggested termination since both twins would be trisomy 21 and the couple did not want to raise a child with Down's syndrome. Our group suggested the possibility that these were fraternal twins with one occurring from natural conception. We suggested to forego termination by D&E but to undergo an amniocentesis at 16 weeks. One twin had obvious cardiac abnormalities by ultrasound and this one was reduced while amniocentesis with karyotype was performed on fetus 2. The results showed a normal male.

One should consider all possibilities before suggesting termination of a very desired pregnancy. This woman had also been advised by other specialists in reproductive endocrinology that conception with her own oocytes (as did occur here) was not possible and she should consider donor oocytes based on her marked diminished oocyte reserve.