Pregnancy and outcome of uterine allotransplantation and assisted reproduction in sheep.

Abstract This pilot study was performed from March 2008 through February 2010 to demonstrate that pregnancy can be achieved in a uterine allograft in the sheep model with the guidance of assisted reproductive technology. Uterine allotransplantation was performed in 12 sexually mature African sheep (Sudanese and Ethiopian). All animals underwent uterine transplantation via a minilaparotomy incision using a Mobius retractor device. A control group of pregnant Romney Marsh sheep with nontransplanted uteri were used to compare fetal development, uterine and placental histologic findings, and blood samples of progeny of the uterine transplant recipient sheep. Fetal size was obtained from ultrasound measurements during the early (crown-rump length) and late (biparietal diameter and abdominal circumference) gestational periods. The primary end point variables included preoperative and postoperative management, embryo transfer protocol, intraoperative assessments, and physiologic cardiopulmonary changes in the lamb during the first 5 hours of life. Four months after the initial uterine transplantation, 5 of 12 uterine allografts were considered candidates for the embryo transfer procedure. Fresh and frozen blastocyst donors were transferred accordingly to the remaining 5 uterine allografts via a minilaparotomy incision. Three of these resulted in pregnancies. One was an ectopic gestation, 1 sheep carried the pregnancy to 105 days, and 1 delivered a fully developed lamb from the transplanted uterus that was delivered via cesarean section. Neonatal lamb blood gas values and chemistry, gross organ examination, and ventilation and respiratory compliance studies yielded results normal for gestational age. This first reported case demonstrates that pregnancy can be carried in an allotransplanted uterus, with the end result a successful delivery.