Risks of donor egg pregnancies revealed

Women who become pregnant using donated eggs have at least three times the risk of developing serious complications, a major study has found.

Such cases are four times as likely to suffer pre-eclampsia and have a threefold risk of high blood pressure in pregnancy compared with other women having fertility treatment, according to new research.

Previous studies have suggested increased risks for those who become pregnant using donor eggs - but it has not been known whether the increased dangers are linked to the older age of women who can no longer produce their own eggs.

Most women who seek donor eggs are over the age of 40, with increasing numbers going abroad because of a shortage of donors in this country.

However, the new study of almost 500 pregnancies compared women with an average age of 35 and concluded that the use of a donated egg itself increased risks, regardless of age.

Almost 18 per cent of women who became pregnant following egg donation suffered high blood pressure, the study found, compared with 5 per cent of other women undergoing fertility treatment.

The risk of pre-eclampsia - a condition linked to high blood pressure, which can be fatal, rose from 2.8 per cent to 11.2 per cent.

Researchers said it was possible that the problems stemmed from changes in the embryo’s immune tolerance when it encountered female genes with different traits to those of the egg recipient.

In future, it might be possible that egg donors and recipients would be matched on genetic factors, to improve immune tolerance, doctors said.

Dr Helene Letur from the Institut Mutualiste Montsouris in Paris said: "Our aim was to find out whether pregnancies from egg donation are genuinely associated with a higher risk of hypertension and pre-eclampsia than those from treatments using the patient's own eggs.

"We would have to conclude from the results that egg donation itself is a risk factor for pregnancy-induced hypertension and pre-eclampsia."

"This has growing importance because of the increasing number of egg donations."

The French study's findings presented to the annual meeting of the European Society of Human Reproduction and Embryology in Munich examined 580 pregnancies between 2005 and 2011, including 217 in which the egg was donated.

Age made only a small difference, while other factors, such as whether women had previously been pregnant or undergone IVF had no significant effect.

Researchers said the high prevalence of high blood pressure in the egg donation group meant doctors and patients need to be more aware of the risks.

Possible biological explanations for the findings include changes in the immune tolerance of the embryo, whose full genome is not concordant with the recipient's.

Dr Letur said the rise in blood pressure could be an attempt by the body to improve exchanges in nutrients and oxygen between mother and foetus.