Massachusetts General Hospital (MGH) researchers have identified what may be a major factor behind the increased risk of two adverse outcomes in pregnancies conceived through in vitro fertilization (IVF). Two papers published in the journal Fertility and Sterility support the hypothesis that extremely high estrogen levels at the time of embryo transfer increase the risk that infants will be born small for their gestational age and the risk of preeclampsia, a dangerous condition that can threaten the lives of both mother and child. They also outline a protocol that reduced those risks in a small group of patients.
Both papers addressed IVF pregnancies resulting in a single live birth, not multiple-birth pregnancies which continue to be the most significant risk factor of any assisted reproduction technology. But even single-birth IVF pregnancies are more likely than unassisted single-birth pregnancies to result in premature delivery, low birth weight and other serious complications. In the January 2013 issue of the journal, the investigators at the MGH's Vincent Department of Obstetrics and Gynecology report that freezing embryos of women who had excessively elevated estrogen at the time of egg retrieval, followed by embryo transfer in a later reproductive cycle when hormonal levels were closer to those of a natural cycle, significantly reduced the percentage of small newborns and eliminated the incidence of preeclampsia in a small group of patients.
"We've known for a long time that singleton pregnancies conceived by IVF were at higher risk of these adverse outcomes, but the reasons were unknown," says Anthony Imudia, MD, of the MGH Fertility Center, lead author of both articles. "Now we know which facet of IVF might be responsible, which will allow us to identify at-risk patients and implement ways of averting those risks."
At most fertility centers, IVF involves a sequence of coordinated events that stimulate the ovar
|Contact: Colleen Marshall|
Massachusetts General Hospital