Remember the days when getting pregnant with twins was a surprise? Now if you’re undergoing fertility treatment, you actually have to decide in advance whether you're up for double trouble by authorizing how many embryos to have implanted in your uterus. But a new study commissioned by the March of Dimes urges doctors to reduce the health problems caused by multiple births by encouraging patients to get pregnant one embryo at a time.
You don’t have to get mowed down by a double-wide stroller on a city sidewalk to know we’re in the middle of a twin epidemic. Twins account for more than 20 to 30 percent of babies conceived via in-vitro fertilization (IVF), which reached an all-time high with more than 165,000 cycles performed in the U.S. in 2012, according to the latest statistics by the Society for Assisted Reproductive Technology. National data show twin births nearly doubled over the last three decades to 1 in 30 babies born in the United States in 2009, from 1 in every 53 babies in 1980.
“In the old days of IVF, we had such low pregnancy rates that we had to transfer multiple embryos at a time just to have a good chance of creating a successful pregnancy,” explains Robert Anderson, MD, a fertility doctor from Newport Beach, California. Yet as fertility medicine improved over the past few decades, rates of multiples eventually spiked until the American Society for Reproductive Medicine tightened guidelines in 2012 about how many embryos could be transferred at a time to prevent another “Octomom,” whose doctor’s license was revoked after he implanted eight embryos into Nadya Suleman’s uterus. The current rule of thumb: one to two for women under 35 and three to five for women in their early 40s, depending on the quality of the embryos.
Yet doctors like Anderson are making the case that we should rethink the trend of buying our babies in bulk, since a singleton pregnancy is better for the health of the mother and baby. The latest numbers show that nearly 15 percent of women under 35 opted for a single embryo transfer in 2012, which is double the number from three years earlier. “Over the years, we grew to accept a certain percentage of twins, but it’s a big problem,” says Anderson. “They’re born three to four weeks premature on average, and there’s an increased risk of birth defects, not to mention the mother suffering from getting gestational diabetes or preeclampsia. A study last year found that medical costs associated with care for the mother during pregnancy and immediately after birth and for the infants up to one year cost on average about $105,000 for twins, compared to $21,000 for a single baby.
Despite the increasing acceptance of the technique known as elective single embryo transfer,the rates are still low compared to some European countries, where IVF is often covered by national health insurance and doctors prefer to implant just one embryo in the vast majority of cases. The concept has been a hard sell on American patients, since many can’t afford multiple IVF cycles and are thrilled at the idea of getting “two for the price of one.” Or they’re older patients who worry they’ll have a harder time getting pregnant the second time around a few years later. “When I talk to my patients about single embryo transfer, the vast majority of their eyes glaze over,” explains Fady Sharara, M.D., a reproductive endocrinologist in Reston, Virginia. “They’ve already made up their minds. They say, ‘Doctor, I’d rather have twins, and then we’re done.’” This twin mindset has become so entrenched among patients that even in a recent study in which they were offered financial incentives to go for a singleton pregnancy, 40 percent still declined.
Yet the math of “more is more” is misleading, and proponents say success rates can be similar. Anderson’s team at the Southern California Institute for Reproductive Sciences published a study last fall in Fertility & Sterility showing that pregnancy rates involving single embryos that had been genetically tested were equivalent to those with a double transfer. Here’s how it works: Although a woman undergoing IVF might produce enough eggs to create a half-dozen embryos, only a certain percentage will be chromosomally normal and likely to lead to a pregnancy. So doctors boost a patient’s chances of success by transferring one of those good embryos, which has a pregnancy rate of up to nearly 60 percent. (National IVF pregnancy rates involving untested embryos, on the other hand, range from 47 percent in women under 35 and 20 percent for women in their early 40s.) She’ll freeze the extra embryos and come back for another pregnancy attempt later, if they first one fails or she wants another child. “You don’t have to have the whole family at the same time,” explains Sharara, pointing out that even though the first cycle might cost around $20,000, including genetic testing, subsequent transfers of frozen embryos will cost a couple thousand each.
Doctors claim they can boost success rates even more by tinkering with the timing of transfers. During conventional IVF, a woman undergoes weeks of hormone stimulation after which her eggs are retrieved, fertilized with sperm, grown into embryos and implanted into her uterus immediately afterwards. But if a woman chooses genetic testing, her embryos will be frozen while she waits for results, and Anderson says she has a better shot of pregnancy if the embryo is transferred during a later month when her reproductive system isn’t flooded with so many hormones.
Fertility medicine has come a long way from throwing a bunch of embryos into a womb and seeing what sticks. Still, the piecemeal approach may not be for everyone, especially older women who want a ready-made family as soon as possible. Also, the insurance companies who do cover IVF, may not cover genetic testing or embryo freezing, which can cost thousands extra. But the growing popularity of the singleton method is a good trend for patients who want more control in shaping the size of their families.