In Sweden, nine women received wombs through doctors’ successful transplants. In this amazing feat of medical surgery, doctors reveal the secrets behind their healing trade.

According to Associated Press, these women were originally born without a uterus or had their uterus removed because of cervical cancer.

While two other operations in Turkey and Saudi Arabia had successfully transplanted wombs, these transplants failed to produce children in these wombs. Sweden stands as the only nation so far to have successfully accomplished this surgery, according to Associated Press. Other countries such as Britain, Hungary and the U.S. have also attempted these surgeries, yet their patients could not sustain pregnancy.

“This is a new kind of surgery,” said Dr. Mats Brannstrom, the chair of the obstetrics and gynecology department at the University of Gothenburg. “We have no textbook to look at.”

This surgery’s precedent occurred also in Sweden, said Canada.com. In September 2012, doctors successfully transplanted a womb between a mother and a daughter. Now these doctors have stepped further into medical success with nine other women. Donors included aunts, sisters, mothers and friends. The oldest donor was in her 60s.

The women were able to make their own eggs with their partners’ sperms, said Canada.com. After doctors froze the embryos, they were able to transplant these embryos into the women’s new wombs through in-vitro fertilization.

Most of these women were able to menstruate six weeks after the transplant, he said, while some had a few minor reactions or infections to the transplant. Otherwise, none received further surgery and were able to go home without any more complications.