"There is a tendency to just put that extra embryo in--or two. And now you have all these babies," said Dr. Mark Sauer of the Center for Human Reproduction
So many parents are faced with multiple births or dealing with the emotional issues and physical risks of "fetal reduction," in which one or more of the fetuses is terminated.
In a new study, British researchers found that if only the two best embryos available were transferred to a woman, the risk of multiple births went down, without affecting overall pregnancy rates.
But fertility specialists in the U.S are critical of the study, saying British doctors are willing to accept a success rate of 18 percent rather than the 25 percent achieved by the U.S. practice of multiple embryo transfer.
"In many cases, putting back only two embryos indeed would lower your multiple pregnancy rate, but also would significantly affect your overall pregnancy rate," Dr. Sauer said.
But there may be a way around the dilemma. To reduce her chance of a multiple pregnancy, Meg Casey opted for a new procedure.
Embryos are grown longer in the laboratory--past the traditional three-day stage to five days, when they're called blastocysts and are more viable. The technique allows doctors to implant only two blastocysts, and actually improves the odds of getting pregnant.
"We've done over 120 patients using this technology and we have established a pregnancy rate higher than 60 percent with just two blastocysts transferred to each patient," said Dr. David Gardner of the Colorado Center for Reproductive Medicine.
Blastocyst transfer isn't perfect yet. Meg Casey was originally pregnant with twins before she miscarried one. But with multiple births, the No. 1 issue in assisted reproduction, the pressure now is to create not just pregnancies, but managable ones.
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