Elevated estrogen at the time of egg harvesting may lead to two common complications with IVF singleton births: premature birth with low birth weight and preeclampsia. Preeclampsia is a dangerous condition that can threaten the lives of both mother and child. Researchers also identified ways that the risk can be reduced.
At-risk patients can now be identified
“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,” explained Anthony Imudia, MD, of the Massachusetts General Hospital (MGH) Fertility Center, lead author of the 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 risk.”
Estrogen must be elevated, but not too elevated, for egg harvesting
While multiple births resulting from IVF continue to have the highest number of complications, singleton births are well known to trigger premature delivery, low birth weight and other serious complications like preeclampsia. When women undergo IVF, a series of events stimulate the ovaries leading to the growth and maturation of several eggs at the same time. The eggs are retrieved for fertilization in the lab. Healthy embryos are then transferred into the woman’s uterus a few days later. At the time of egg harvesting, estrogen levels must be high. Research published in Fertility in Sterility in June 2012 showed that women whose peak estrogen levels were at or above the 90th percentile had a nine-fold greater risk of a small infant and a five-fold risk of preeclampsia.
New recommendations for lowering risk can now be made
Following up on that research, the team advised women whose estrogen levels were extremely high at time of harvesting of the risks. They were advised of alternatives. The women could either postpone the procedure or freeze the eggs for later implantation. Only 10% of women who chose embryo freezing experienced the complications compared to 35% for the women who went ahead with implantation while their estrogen levels were high.
“If other centers validate our findings by following the same approach and achieving similar outcomes, we would recommend that each patient’s hormonal dosage be adjusted to try and keep her estrogen levels below 3,000 pg/mL,” said Imudia.
Source: MedicalNewsToday, Fertility and Sterility, MGH