An increasing amount of research, including a study published in the March 22 edition of the journal Lancet, suggests that transferring one embryo for an in vitro fertilization treatment is as likely to result in pregnancy as transferring multiple embryos, but some physicians say that most IVF patients are not interested in single-embryo transfer, the Boston Globe reports. According to the Globe, the likelihood of multiple births, premature birth and low birthweight increase with the number of embryos transferred during an IVF procedure. The Lancet study, led by Bart Fauser of Utrecht University, compared a group of women under age 38 who underwent a single-embryo transfer and a milder ovarian stimulation with a group of women who underwent multiple embryo transfers and standard ovarian stimulation. The multiple embryo group had a higher pregnancy rate after one or two IVF cycles, but the rate of the two was the same after one year. According to the Globe, an increasing number of physicians are advocating single-embryo transfers. Some physicians say that most IVF patients are not interested in single-embryo transfer because it could take longer to become pregnant and because research shows most patients want twins. "Those who have been on the long journey of infertility are quite desperate and are willing to accept the risk of multiples," Samuel Pang -- medical director of the Reproductive Science Center in Lexington, Mass. -- said. Fauser said the IVF industry should change the way success is defined. According to the Globe, U.S. physicians focus on pregnancy rates because the government requires that clinics report success rates per IVF cycle. Insurance companies also consider the rates when determining which clinics to include in their network. Fauser said that achieving a pregnancy should not be "good enough," adding, "Couples don't come for pregnancy, they come for a healthy child." Elizabeth Ginsburg, medical director of the IVF center at Brigham and Women's Hospital, said that until physicians are able to identify which embryos will lead to pregnancy, women undergoing mild IVF will have to wait too long before becoming pregnant. According to the Society for Assisted Reproductive Technology, in 2005, about 2% of IVF cycles performed at member clinics nationwide involved single-embryo transfers (Elton, Boston Globe, 3/26).

The study abstract is available online.