Two years ago a Swedish research team announced that they had performed a revolutionary feat: For the first time they had helped a woman born without a uterus give birth to her own child. They had transplanted a uterus from a 61-year-old volunteer into a 35-year-old patient, waited a year for the recipient to heal and finally implanted an embryo that had been previously created through in vitro fertilization. The baby boy was born prematurely—32 weeks into the pregnancy—but ultimately he survived and is now a healthy infant in day care.

That experimental surgery was a watershed for the reproductive research community, and ignited hope that women who are born without a uterus or lose it to disease could have a chance at pregnancy. Other successful births from that same research team have followed—yet no other doctors’ operations have led to a similar birth following a uterine transplant. In March the first uterus transplant in the U.S. failed after the 26-year-old recipient had complications that forced her Cleveland Clinic surgeons to remove the organ a day after it was implanted. But that hospital and at least five others are now planning to move ahead with their own pilot trials for the procedure in the coming years, using uteruses from volunteers or cadavers. Three other U.S. institutions are among them—Baylor University Medical Center at Dallas, Brigham and Women’s Hospital and the University of Nebraska Medical Center.

So what does it take to navigate such a challenging procedure? Scientific American spoke with the lead surgeon from the Swedish research team, Mats Brännström, who is a gynecologist at the Sahlgrenska Academy at the University of Gothenburg. He discussed what obstacles must still be overcome with the procedure and his advances in performing uterine transplants that support future pregnancies.

[An edited transcript of the interview follows.]

How many uterine transplant surgeries have there been so far?
Worldwide, now 14 or 15 have been done. But not all of these cases have been successful. There was one in China in November. There was also one in the Czech Republic in April, which was covered by the Czech media, and there was the Cleveland Clinic case, of course. There were nine cases in Sweden. But two of those [transplants] were removed during the initial months. There was also Saudi case where it was removed after 99 days and a case in Turkey with no pregnancy yet.

How many of those surgeries have led to a woman with a transplanted uterus birthing a child?
We are the only ones who have produced live births. We have five babies now and we have some ongoing pregnancies also.

There are now four pilot trials in the United States and two in Europe registered with, in which surgeons are trying to emulate your successes. What still needs to be perfected with this procedure?
My team has gotten permission to do a second trial in Sweden that is robotically assisted. The robot will take the organ out from the live donor. Right now that takes us 11 to 13 hours to do. We think the robots will be able to decrease that perhaps to six or seven hours. It is reducing the surgical time that is important. The recipient surgery is only about three or four hours and is straightforward, but to take it out from a living donor is still very difficult.

Are you using a da Vinci robot?
Yes, that is the only one on the market right now to help with this. On Monday [June 6] a team from Brigham and Women’s is coming here—we have practiced together on sheep and cadavers before. We are all going to Belgium to a training center to conduct training with robots together. We will be working on cadavers with the robot.

What enabled you to be able to successfully perform uterine transplants in recent years, and for those women to bear children?
I think our success is that we prepared so meticulously by looking at all the difficult parts in animal models and learning how to solve those tricky parts. And then when we went from baboons we had a very successful and optimized procedure. We were the same team that worked on the sheep and baboons—not just the doctors—the OR [operating room] nurses are very important, too. We are a team with a team effort.

What was difficult with the baboons?
They need so much more immunosuppressant drugs—a much higher dosage than in humans. The most challenging surgery is in the human. It is actually easier in the baboon, and that was unexpected.

Why is that?
Humans are more difficult because the pelvis is like a funnel and it is difficult to get access, compared to the baboon. It is much deeper in humans. We are actually working in a very sensitive area, and it is anatomically difficult because it is a small vessel deep down with bad access. That is why we think a robotic approach is better.

These transplants are intended to be temporary—removed after one or two children are born, right? That’s unique for an organ transplant.
Yes, that’s the only organ transplant so far that is just temporary and just used for some time. The advantage of that is that you don’t have to be on immunosuppression for the long side effects. So far, we have removed three of these [uteruses] after babies were born.

I know delivery is by cesarean section in these patients—in part to reduce stress on the transplanted organ. Can you talk about how a pregnancy with a donated uterus differs from a traditional pregnancy overall?
The delivery is always by cesarean section. The uterus does not have the same nerves [the nerves are not transplanted], so the women do not feel contractions the same way. They also may not feel if the fetus is kicking. We have to survey the pregnancies a little more closely to make sure they are not having contractions that they do not know about. Many of these women have a rare condition called Rokitansky syndrome and were born lacking the upper part of the vagina in addition to the uterus, so they typically have a neovagina that is surgically made. Most of the women have been operated on for this, to create a neovagina. It is a procedure where you extend the usual vagina by some kind of forced dilation surgery. Otherwise, there is no difference.