Does IVF increase the chance of identical (monozygotic) twins?
It does, at least according to a study in the July 2010 issue of Fertility & Sterility.
The authors surveyed 4976 clinical pregnancies from one large IVF center and found ninety-eight cases of monozygotic twins (MZTs) were diagnosed after first-trimester ultrasound evaluation (2% incidence). In naturally conceived pregnancies the incidence is about 0.25-0.5%.
The incidence in women transfering embryos from …