A new study suggests that women who use donated eggs to get pregnant by in vitro fertilization (IVF) might be more at risk for a potentially dangerous complication than women who use traditional IVF methods.
Women who use IVF -- in which an egg is fertilized outside the body, then implanted into a woman’s uterus -- are already believed to be at an increased risk for preeclampsia -- a condition that occurs when a woman’s blood pressure rises during her second or third trimester and her kidneys fail to continue to retain protein.
Now, the study suggests that using donated eggs could possibly increase that risk even further. But doctors say more research is needed to confirm the findings.
Dr. Peter Klatsky, the lead author of the paper from Women and Infants Hospital in Providence, Rhode Island, said results from the study “should not be alarming or frightening.” Rather, the findings could help doctors understand what causes the condition and how to counsel patients who are at risk.
Preeclampsia is not a well-described condition, although being relatively common. About one in 20 pregnant women develop the condition, and the only cure is to give birth.
For those women who carry a baby to full term -- at least 37 weeks -- doctors can induce labor. In those who are in the earlier stages of pregnancy, doctors can only closely monitor the symptoms to make sure they do not progress.
Studies in the past have shown that women who use donor sperm and those who get pregnant with a new sexual partner have higher rates of preeclampsia than in other women. Those studies suggested that the condition could be related to the body’s immune response to cells it doesn’t recognize.
Klatsky and colleagues decided to start their own study to test if that pattern held true for eggs that the body would consider “foreign.”
The team of researchers compared 77 women who had given birth using donated eggs between 1998 and 2005 with 81 similar women who had gotten pregnant using IVF with their own eggs.
The researchers noted how many women in each group were diagnosed with either preeclampsia or pregnancy-related high blood pressure, as well as how many gave birth to their babies prematurely.
Their results show that about 5 percent of women who used their own eggs for IVF developed preeclampsia, compared to nearly 17 percent of women who used donor eggs. Women using donor eggs were also more likely to get high blood pressure without kidney problems and to deliver premature.
Their findings also showed that women who got pregnant using embryos that had been frozen and then thawed were more at risk for preeclampsia than women using fresh embryos. Klatsky said it’s a possible effect that is worth looking into with future studies.
Dr. Sacha Krieg, an obstetrician who studies infertility at the Kansas University Medical Center and was not involved with the study, agreed that doctors should counsel patients at increased risk for preeclampsia and monitor them more closely during pregnancy. But cautioned against trying to draw too much of a conclusion from a small study.
Krieg told Reuters Health she hopes that future studies will start with women who are just getting pregnant and track their health as they go through their pregnancy. While harder to conduct, such studies can often give researchers more accurate information.
However, both she and Klatsky hopes that the current study will give researchers more clues about how preeclampsia develops.
Having more information about the condition could help doctors “develop better treatments and better ways to prevent it, and better ways to counsel patients about their risks,” Klatsky told Reuters.
There are still signs that preeclampsia has something to do with the body’s immune response when it recognizes foreign cells. It would make sense, says Krieg. “We know that the immune response is important for both implantation and development of the fetus.”
Doctors need to learn more about how a fetus implants in the uterus, she added, because this is probably where the early stages of preeclampsia start, even if women do not show symptoms until much later.
Klatsky said the main message of the study is that doctors should be aware of possible risks to their patients, and most importantly that researchers should keep tracking the immune system response in pregnant women.
Results of the study are published in the journal Obstetrics & Gynecology.