Conjoined twins after single blastocyst transfer: a case report including detailed time-lapse recording of the earliest embryogenesis, from zygote to expanded blastocyst.

Conjoined twins are estimated to occur in 1:50 000 pregnancies. Eighteen cases of pregnancies achieved by ART have been published of which three were achieved after single embryo transfer, allowing discussion of embryo characteristics. We report, to the best of our knowledge, the first case of parapagus conjoined twins after ART.