As in vitro fertilization has become an increasingly common fact of life for those seeking to start a family, so have twins, triplets – or more, thanks to the transplantation of multiple embryos. The CDC reports that the twin birth rate rose 76 percent from 1980 to 2009 while triples and higher-order multiple births rose a whopping 315 percent.
But the tide of multiple births may be ebbing as an increasing number of women are opting to transfer a single embryo during IVF.
According to experts, women usually have two or more embryos transplanted in order to boost the chances for a baby. (In the rare case of “Octomom” Nadya Suleman, eight embryos were implanted, resulting in eight live births.)
Thanks to better technology, though, single-embryo transplants are now almost as effective as multiple-embryo transplants – with far fewer health risks to both mom and baby. High-profile cases like Suleman’s have also raised awareness about the risk of implanting too many embryos.
“It’s something that will contribute to healthier pregnancies,” says Dr. Louis Weckstein, owner of the Reproductive Science Center, a fertility clinic operating in the San Francisco Bay area for 30 nearly years. “We educate patients that transferring one embryo in select situations is almost equally as successful as multiple transfers, and there are a number of studies largely confirming this."
At Weckstein's clinic, the percentage of elective single-embryo transfers has doubled from 2009 to 2010, to 30.5 percent of 593 cycles – about double the national average for single-embryo transfers. Industry guidelines recommend that no more than two to five embryos be implanted per IVF cycle, depending on the mother’s age and prognosis.
“If you transfer a single embryo in women 37 or younger, or with donor eggs, and it’s a high quality embryo, we really do not see significantly different pregnancy rates versus when you transfer two high quality embryos,” Weckstein says, adding that other pioneering clinics have similar or better rates.
A big hitch may be getting more patients to go along with it.
Weckstein’s success notwithstanding, the Society for Assisted Reproductive Technologies reports that only around seven percent of women under 35 chose an elective single-embryo transfer in 2009. IVF can be grueling and expensive, and the notion of doubling your odds can be tempting, even if it’s not necessarily how things work.
“I am 42 and don't want to wait a year to try again,” says Celeste of Folsom, Calif., who asked that just her first name be used to protect her privacy. “I don't want to go through an IVF cycle again, including those awful hormones and butt shots. With twins, I get my two babies in one pregnancy, and I'm done."
Deciding whether to go with single or multiple embryos can also make for a lot of economic and emotional pressure for patients, says Dr. Natalie Cekleniak, of the Institute for Reproductive Medicine at Saint Barnabas Medical Center in Livingston, N.J.
“Patients are so desperate and so sad they cannot see things objectively," she says. "All they’re looking for is, ‘Give me my best chance to be pregnant.' They’re not worried about twins, because they don’t see the risks involved.”
And with multiples, the chance of birth risks does increase. About 60 percent of twins and 90 percent of triplets are born prematurely, with a greater risk of stillbirth, death in infancy and health problems that can last a lifetime. A multiples pregnancy is also riskier for moms, increasing the likelihood of the hypertension condition known as preeclampsia and gestational diabetes. Moms with multiples are also more likely to receive a C-section.
“Probably every other month, we hear of patients who had twins and will come back and say to me, 'I wish we had listened to you and put in a single embryo. The babies were born at seven months and were put in the NICU [the newborn intensive care unit],'” Weckstein says.
Hope lies in better lab technology. Genetic testing and other technology help determine the fittest embryos. And the longer the embryos can grow in the lab – in the proverbial “test tube” – before implantation, the better their chances of survival. Some clinics can now wait until the blastocyst stage – which occurs five to eight days after fertilization -- before implantation.
“The goal is to implant the absolutely healthiest embryo we can find,” Weckstein says.
Unfortunately, not every clinic has the technology and the expertise to achieve consistently positive outcomes with single-embryo transfers, which is why only about 100 existing clinics are making a push toward them, says Weckstein.
“Centers that have difficulty growing embryos to the blastocyst stage will often put in more because their embryos don’t grow as well," he says. "So they put in three or four, and they all stick. That’s when the disasters happen."
Carla B., a 33-year-old expectant mother from Calgary, Alberta, who asked that her last name not be used, is pregnant thanks to a single-embryo transfer IVF. She says a mandatory video at a regional clinic about the risk of multiples swayed her decision.
“We would move mountains to avoid our children having poor health or pain, so the time to start being a parent was even before they were born,” she says. “For me it all boiled down to one question: ‘Can I live with any health issues my child may have because of a multiple birth, knowing it was due to my choice to have multiple embryos transferred?’”
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