One embryo is all it takes for a successful IVF: Study

By Dr. Ananya Mandal, MDOct 25 2011

Doctors practicing IVF often transferred multiple embryos to a woman’s body at once, in the hope that at least one of them would lead to a successful pregnancy. That changes now as a new study from researchers at the University of Iowa in Iowa City found that women who had only one embryo transferred during IVF didn’t have lower chances of getting pregnant, but they did have a lower risk of giving birth to twins than women who had multiple embryos transferred.

Twins, triplets or other multiple-set children are not necessarily undesirable, but according to the American Society for Reproductive Medicine, multiple births increase the likelihood that mothers and babies will have health problems, such as diabetes, during pregnancy, premature births and pre-eclampsia.

According to study’s author, Jessica Kresowik, her fertility clinic instituted a single-embryo policy in 2004 for women age 38 and younger getting their first IVF and who had a good chance of getting pregnant. According to the American Society for Reproductive Medicine, no more than two embryos should be transferred for women under 35. Babies conceived through IVF account for just one percent of births each year, but IVF is responsible for 17 percent of twins, Kresowik added.

When she and her colleagues studied the numbers of live births before and after the policy, they found that the use of single embryos were just as effective at leading to live births, and maybe even more effective – 51 percent of patients gave birth to live babies before the policy, and 56 percent did after the change to single embryos. Most importantly, the proportion of women with multiple births dropped from 35 percent to 18 percent.

Dr. Bradley Miller, who specializes in IVF at the Reproductive Medicine Associates of Michigan in Troy, Mich., said he believes policies like the one at Kresowik’s clinic are the way of the future. “Complications from premature births can be lifelong medical issues or the babies simply don’t survive,” Miller said. “In the long term, these single-embryo practices are going to provide for healthier babies and obviously decrease rate of multiples across the nation.”

However, Miller said many patients often request multiple embryo transfers, despite knowing the risks. “They want to have a better chance of pregnancy and they’re not necessarily opposed to having twins,” Miller said. “The crucial part of single-embryo policies is educating the patient that having twins isn’t necessarily going to have a good outcome every time.”

“A policy like this is a great idea,” said Judy Stern, a fertility specialist at the Dartmouth-Hitchcock Medical Center in New Hampshire, who wasn't involved in the study. “You really can move toward single-embryo transfer and have it give you great success rates, and really low multiple rates,” she said.