First human pregnancy from nuclear transfer: lasted until 29 weeks' gestation.(Gynecology)

SAN ANTONIO -- An experimental infertility therapy involving the transfer of a patient's pronucleus into a donated enucleated oocyte produced the world's first reported human pregnancy from nuclear transfer in China, Dr. John Zhang reported.

His announcement, made at the annual meeting of the American Society for Reproductive Medicine, immediately generated controversy, in part because the procedure closely resembles the technique used for cloning.

"Even though it involves a similar technique, this is nothing close to cloning," said Dr. Zhang, a fellow in reproductive medicine at New York University.

The work, pioneered by Dr. Zhang and Dr. Jamie Grifo, head of the division of reproductive endocrinology and infertility at NYU, was the culmination of 6 years of research, first in New York and then (with the local ethics board's approval) at Sun Yat-Sen University of Medical Sciences in Guangzhou, China.

The pregnancy, in a 30-year-old Chinese woman, did not continue past 29 weeks' gestation. Fetal reduction from a triplet to a twin pregnancy was performed 33 days after embryo transfer. The second fetus was delivered at 24 weeks and died of respiratory distress after premature rupture of membranes. The third fetus was delivered at 29 weeks after intrauterine fetal demise caused by cord prolapse.

Dr. Zhang said nuclear transfer holds therapeutic potential for enabling women with mitochondrial disorders and certain oocyte defects to have children.

"Current genetic tests and counseling cannot help these patients, but oocyte genetic diagnosis and, potentially, nuclear transfer could," he said.