Multiple Embryo Transfers: Time for Policy

The birth of eight children to Nadya Suleman led to an outcry over the common practice in assisted reproduction of transferring multiple embryos to a woman’s uterus. The practice increases the chances of a live birth, but also raises the likelihood of multiple births, with their risks and costs. It is time for the United States to enact policy that will limit the number of embryos transferred to a woman.

Health Problems

In vitro fertilization in the United States often leads to multiple births. More than 30 percent of deliveries using fresh embryos and nearly 25 percent of those using frozen ones result in multiple births,¹ with 48 percent of all IVF infants born in multiple births.²

Any multiple birth raises health risks. Among twins, more than 60 percent are born prematurely; among triplets or other multiples, more than 95 percent are premature.³ Primarily for this reason, IVF twins, triplets, and other multiples are more likely than singletons to require neonatal intensive care, to develop cognitive and physical disabilities, and to die. Twins have an infant mortality rate four to five times that of singletons; triplets have an eight- to tenfold increase.⁴ These infants are also at increased risk for cerebral palsy, deafness, and blindness, and they exhibit delayed language development and lower verbal intelligence.⁵ Multiple births pose greater health risks for the mother as well. They increase the risk for maternal hypertension, preeclampsia, hemorrhage, Cesarean section, and death, as well as for postpartum depression and high parenting stress.⁶

These risks drive up the cost of health care. In one study, the delivery-associated hospital costs were twice as high per child for twins as for singletons, and four times higher for triplets.⁷ Lifetime medical costs may be two hundred times higher.⁸

IVF patients might be willing to assume the increased risks of multiple births in order to increase their likelihood of having at least one child. Studies indicate, however, that the success rate improves only marginally with multiple transfers, and some studies have found no difference. In one study involving women younger than age thirty-six with good-quality embryos, double-embryo transfers increased the live birth rate from 39 to 43 percent, but the multiple birth rate increased from 1 to 33 percent.⁹ In another study of women with good prospects for successful IVF, those with single-embryo transfers had the higher live birth rate—41 percent versus 36 percent for the double-embryo transfers. Moreover, the multiple birth rate rose from zero for single-embryo transfers to 37 percent for double-embryo transfers.¹⁰ For women who have less favorable prospects, on the other hand, a double-embryo transfer may significantly increase the chances of success. In one study, it doubled the pregnancy rate.¹¹

To be sure, there are other tradeoffs between single- and double-embryo transfers. To achieve a comparable overall live birth rate, women using single-embryo transfers may need to undergo two IVF cycles instead of one, doubling their cost of treatment. And older women who want two children may prefer to have twins rather than successive singletons. Because of the decline in fertility with advancing age, a forty-year-old woman may not be able to become pregnant a second time.¹²

The Response

Professional guidelines discourage multiple-embryo transfers, especially for women under age thirty-five. Suleman’s physician transferred six embryos for her pregnancy, but Society for Assisted Reproductive Technology and American Society for Reproductive Medicine guidelines indicate that she should have received only one or two. Yet IVF procedures with two or more embryos are still common. Nearly 90 percent of embryo transfers involve at least two embryos, and more than 40 percent involve at least three.¹³ To be sure, the percentage of IVF procedures with more than two embryos has recently declined, but the shift has been to double- rather than single-embryo transfers. As a result, triplet or high-order births have declined while twin births have increased.¹⁴

If professional guidelines have not been effective, what other approaches might make sense? This depends on why physicians...