Multiple Births From In Vitro Down

Jain and study co-author Mark D. Hornstein, MD, say the findings validate the notion that decreasing the number of transferred embryos results in a reduction in multiple-infant pregnancies without affecting overall pregnancy rates.

In an effort to reduce high-order pregnancies, several European countries have passed laws restricting the number of embryos that can be transferred each time assisted reproduction techniques are attempted. There are no such restrictions in the U.S., but the nation's top infertility group now has guidelines that call for a maximum of two embryos transferred per attempt at assisted reproduction for infertile women with the most favorable prognoses for becoming pregnant -- usually women under 35 years old.

In women with a below average chance of becoming pregnant with assisted reproduction techniques, a maximum of five embryos are transferred. These are women who are 45 and older and who have had numerous failed attempts at assisted reproduction.

Twin Births Troubling

American Society for Reproductive Medicine Executive Director Robert W. Rebar, MD, tells WebMD that the group is considering tightening the guidelines even further to address the issue of twin births.

"The fact that we have not lowered the percentage of twin births is of concern," he says. "Most people don't appreciate the fact that, like higher-order births, twin births are associated with greater obstetrical and neonatal morbidity and mortality."

He says single-embryo transfer will become a more attractive option for many infertile couples as assisted reproduction laboratories get better at freezing embryos.

"It is almost as cheap to freeze embryos and implant them one per cycle as it is to implant multiple embryos during a single cycle," he says. "This is an evolving practice, but I do believe that it is the direction that we are going in and that it will lead to a reduction of multiple births."

SOURCES: Jain, T. The New England Journal of Medicine, April 15, 2004; vol 350: pp. 1639-1645. Tarun Jain, MD, reproductive endocrinology fellow, Brigham and Women's Hospital, Boston. Mark D. Hornstein, MD, director, Center for Reproductive Medicine, Brigham and Women's Hospital; associate professor of obstetrics, gynecology and reproductive biology, Harvard Medical School, Boston. Robert W. Rebar, MD, executive director, American Society for Reproductive Medicine, Birmingham, Ala.