Doctors have come across a rare case, which they say is the second one they have seen. This follows a case of semi-twins.
Four-year-old twins in Brisbane, a boy and a girl, are identical twins on their mother’s side, but fraternal on the father’s side, as the sperm is different. The children are therefore midway between fraternal and identical.
Experts describe this as a rare case, as in similar cases the babies generally do not survive.
Professor Nicholas Fisk, who led the team looking after the mother and the twins at birth, said they discovered this when a scan was made during pregnancy.
This is the first time ever that semi-identical twins have been identified during pregnancy. During the first six weeks the twins appeared to be identical, but at 14 weeks the ultrasound identified a boy and a girl, which is not possible for identical twins.