BioEd Online

Women who receive eggs from relatives for fertility treatments have a healthier pregnancy than those who use eggs from unrelated donors, researchers say.

Sun-Hwa Cha and her colleagues at the Sungkyunkwan University School of Medicine in Suwn, South Korea, found that using unrelated eggs significantly increases a patient's risk of developing chronic high blood pressure during pregnancy. They present their findings at the European Society for Human Reproduction and Embryology meeting in Copenhagen this week.

About 10% of first pregnancies cause high blood pressure, or hypertension, explains Fiona Broughton Pipkin, an expert in perinatal physiology at the University of Nottingham, UK. About 10% of these women develop a more severe form known as pre-eclampsia; in Britain, about 10 women die each year from this condition. The illness can also force doctors to deliver the baby before it has had a chance to fully develop. Doctors currently cannot effectively treat this condition.

For reasons that aren't entirely understood, the risk of developing hypertension during pregnancy increases if a woman has had in vitro fertilization (IVF). And now it seems the risk is even greater if the eggs come from a non-relative.

Tense moments

Cha and her colleagues studied 61 pregnancies that resulted from egg donation and compared these with a control group of standard IVF pregnancies, in which the eggs come from the woman who wants to get pregnant. Hypertension attributable to the pregnancy struck 12.5% of women in the first group, as opposed to 3.7% of those who had the more common procedure.

But the researchers discovered another striking difference in the group receiving donated eggs: the risk of high blood pressure increased by more than fivefold in cases where a woman had received an egg from a unrelated person, but only twofold when the egg came from a sibling.

The researchers have yet to prove why eggs from unrelated donors make complications more likely, but they believe the answer lies in how the immune system reacts to the developing fetus. The presence of foreign proteins on these eggs could trigger an abnormal response in the patient's immune system leading to hypertension, Cha and her team say.

Broughton Pipkin agrees that the immune system could be to blame. She adds that some people believe an immune response against cells in the uterus might lead to the release of reactive oxygen molecules in the blood, which could damage the blood vessel cells that protect against hypertension. But there is still much debate over the issue, she says.

The Korean researchers say that their findings should encourage sisters to consider donating eggs. "Donation from a sibling would improve the outcome both in terms of the well-being of the pregnant mother and the health of the baby," says Cha.