Limiting embryos
In vitro fertilization has come a long way since the birth in 1978 of the world’s first “test tube” baby, Louise Brown. Thanks to improved technology, the procedure has a higher success rate than it did a decade ago and doctors now report fewer multiple births.
A key reason for fewer triplets, quads and quints is that doctors began voluntarily limiting the number of embryos they implant in infertile women. And yet, reproductive specialists encounter patients every day who, because of the expense, emotional toll or advancing age, say they’d prefer twins -- or more.
“I had a patient in the office today who’s 40 and who wants twins. In fact, this particular couple wasn’t particularly opposed to triplets,” said Dr. Mark D. Hornstein, director of the Center for Reproductive Medicine at Brigham and Women’s Hospital in Boston.
Hornstein advises couples that the major complication of assisted reproductive techniques, such as in vitro fertilization, is becoming pregnant with multiple fetuses. Such a pregnancy increases the likelihood that a woman will experience bleeding or high blood pressure. It also raises her risk of delivering a premature or disabled child, with the accompanying economic and emotional stress.
In a study published last week in the New England Journal of Medicine, Hornstein and lead author Dr. Tarun Jain reported that the number of live births among women undergoing assisted reproduction rose from 19.6% to 27% between 1995 and 2001 -- years for which the federal Centers for Disease Control and Prevention have published data from fertility clinics nationwide. That finding reflects the fact that doctors and others involved in fertility treatment are continually enhancing their skills.
Said Hornstein: “It’s a rising tide and all boats are rising.”
In the same period, the average number of embryos transferred in each attempt at pregnancy dropped from four to three. The percentage of in vitro-assisted pregnancies involving three or more fetuses declined from 11.4% to 7.4% between 1997 (the first year for which data on triplets were available) and 2001. The rate of twins from in-vitro pregnancies held steady, even as the nation’s overall rate of twins rose.
Reproductive specialists are having more conversations with their patients about limiting embryo transfers. In an interview, Jain said he had just seen a woman in her early 30s who sought his help after two failed IVF attempts. She wanted him to transfer three embryos. But based on her age and good embryos, Jain recommended transferring two. The American Society of Reproductive Medicine and the Society for Assisted Reproductive Technology adopted voluntary guidelines for embryo transfers in 1998 and revised them in 1999. The recommended number of embryos to be transferred ranges from two (in women under 35 with enough good-quality embryos to both implant and freeze for later use) to five (in women age 40 and older or in those who have undergone multiple failed in-vitro attempts.)
Publication of the findings follows the April 1 release of a reproductive technology report from the President’s Council on Bioethics. That panel recommended that physicians and professional societies “take additional concrete steps to reduce the incidence of multiple embryo transfers and resulting multiple births.”
“We think that decision is best left to the clinician and his or her patient,” Hornstein said. “There may be individual circumstances where you want to transfer more embryos ... but an exception should truly be an exception.” Despite the overall progress, doctors still face patients who desire multiple births.
In the March issue of Fertility and Sterility, reproductive endocrinologists from the University of Iowa who surveyed more than 400 infertility patients found that 20.2% said they would prefer a multiple birth. Of that group, 94% hoped for twins; 2% wanted triplets and 4% said they’d be happiest with quadruplets or more.
“Thus a sizable minority prefers the situation that the medical community is trying hard to avoid,” the authors wrote.
Dr. Alan H. DeCherney, a UCLA professor of obstetrics and gynecology, said some doctors might feel pressure in certain cases to transfer more embryos, especially for women who lack health insurance or whose medical plans don’t cover IVF.
“You have somebody sitting in front of you. It’s her third IVF cycle; she’s 36 years old; she’s got four embryos. It’s cost her $40,000 to $50,000. What are you going to do?” DeCherney said.
