An in vitro fertilization (IVF) technique that minimizes the risk of multiple births appears to be effective for those women who are over 35, say researchers at the Stanford University School of Medicine. More than half the women in the study became pregnant after undergoing the procedure, called a single blastocyst transfer, which transferred just one embryo into the womb. Nearly two-thirds of IVF procedures in the US are performed on women older than 35, and the study's senior author, Amin Milki, believes the findings are good news for those women who wish to become pregnant with just one child.
"Although these results represent a selected group of patients, we believe that they should serve as encouragement to patients and providers who are considering single blastocyst transfer in the older IVF population," Milki said.
The American Society for Reproductive Medicine currently recommends that doctors transfer two or more embryos into women older than 35, in an effort to maximize a patient's chance of becoming pregnant. This practice can lead to twins or higher-order multiples - as well as subsequent health risks - but Milki said this doesn't stop most patients from undergoing the procedure.
"Many patients would prefer not to have two babies at once," said Milki. "But because the success rate is higher when multiple embryos are transferred, women are willing to take the gamble."
Scant data exist on single blastocyst transfer in women over 35, so Milki and his colleagues decided to review the outcomes of older patients who underwent the procedure at Stanford. Milki said the procedure had been offered to those women with good-quality embryos, and the patients who elected to have only one embryo transferred did so as a way to avoid twin pregnancy. He noted that half the patients already had one child and wanted just one more, while others hoped to avoid the health complications associated with carrying multiples.
Milki did caution that the findings are not applicable to every woman over the age of 35. For women with lower-quality embryos, transferring two or three embryos might be the better way to pursue a pregnancy.
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Source: Stanford University Medical Center
