In a case of mistaken identity, an Italian woman is about five months pregnant with another couple's twins.

The mix-up occurred at Rome's Sandro Pertini Hospital on December 4, when four women were receiving in vitro fertilisation treatments (IVF).

IVF involves fertilising an egg by sperm in a laboratory. The fertilised egg is then inserted into the mother's uterus with the hopes of successful implantation and pregnancy.

Corriere della Sera and her husband had a successful implantation, but soon found out that the DNA of the twins were not theirs.

The Telegraph reported that one of the women undergoing IVF on December 4 had a surname very similar to della Sera's. It is possible that the staff misread the medical charts, and accidentally inserted the wrong embryos, or that della Sera misheard the name called in the waiting room.

Although understandably shocked, the soon-to-be new mother is determined to continue her pregnancy.

"If she had wanted an abortion she would have already done it," Michele Ambrosini, della Sera's attorney, told The Telegraph.

When the twins are born, Mrs. della Sera will be raising them as her own, and the children will legally be hers. Under Italian law, whoever gives birth to a child is the legal mother. The biological parents in the IVF mix-up will have no grounds to contest parental rights.

It is unknown whether other women are carrying misidentified embryos, or what happened to della Sera's embryos.

The Italian health ministry is investigating a case that it says should never have happened.

"The national standards on assisted fertilisation, which are based on European directives, are very rigorous, and if applied correctly, guarantee the traceability of all biological material used in the reproduction process," Health Minister Beatrice Lorenzin said, according to MSN.

The news site also reports that all embryo implantations at Sandro Pertini have been suspended until further notice.