Swedish doctors say they have performed the world's first mother-to-daughter uterus transplants, but won't consider themselves successful until one of the two transplant recipients produces a healthy baby.

The leader of a medical team at the University of Gothenburg said this week that more than 10 surgeons worked on the operations Saturday and Sunday, transferring the uteruses of two women past child-bearing age to their daughters, both in their 30s.

One of the younger women was born without a uterus, and the other lost hers to cancer years ago. Doctors say they chose mother-to-daughter donors and recipients to reduce chances of rejection, and because the donate uteruses had already proven fertile. Experts say they believe post-menopausal uterus can still host a fetus when transplanted to a younger woman.

The medical team says the women must wait at least a year before trying to get pregnant. The women are expected to use in vitro fertilization and then would deliver by caesarean section to avoid damaging the uterus.

The doctors say they plan to remove the uteruses after the women give birth to a maximum of two children, to avoid the young mothers taking unnecessary immunosuppressive drugs, which meant to keep the body from rejecting the transplanted uterus.

The experts say they will not know if the entire procedure has been successful until at least 2014, after one of the recipients has borne a healthy child.

Critics of the procedure have raised concerns that anti-rejection drugs could hurt a baby developing in the womb. But one of the surgeons, Michael Olausson, on Tuesday told reporters that anti-rejection drugs have not been harmful to fetuses in expectant mothers who have undergone other organ transplants.

These are not the first-ever uterus transplants. Turkish experts accomplished that in 2011. It is not clear whether that patient has begun fertility treatments yet.