The research showed that women who used donor eggs in their treatment were four times more likely than women using their own eggs to get pre-eclampsia, a mostly benign but occasionally serious condition characterised by high blood pressure (hypertension) and protein in the urine.
Dr Hélène Letur from the Institut Mutualiste Montsouris in Paris, who presented the study at a fertility conference, said: 'This study confirms several other reports in the literature, with a large sample and matched control group. We would have to conclude from the results that egg donation itself is a risk factor for pregnancy-induced hypertension and pre-eclampsia'.
Overall, 18 percent of the 217 women who became pregnant with donated eggs developed hypertension compared with five percent of women pregnant after 'normal' IVF. The risk of pre-eclampsia after IVF with donated eggs was 11 percent, increased from three percent in other patients.
Because women who use donated eggs tend to be older, it was not previously known whether the increased complications seen in these pregnancies were a result of age. The study looked at French patients because egg donation in the French social security system is restricted to women under 43, many of whom required donated eggs due to premature menopause. In fact, increased patient age produced only a small increase in risk. There was no significant effect on hypertension risk from previous pregnancies, previous IVF cycles or the use of preserved embryos.
Dr Letur urged patients and obstetricians to be aware of potential risks in egg donation: 'Preventive measures and care are necessary, with screening for risk factors for hypertension such as obesity and diabetes and early treatment'.
The authors suggest that immune system incompatibility between the mother and the genetically unrelated embryo may be behind the increased risk, but did not test this hypothesis in the study.
Egg donation can be used in IVF for women who, because of their age or a medical condition, no longer produce viable eggs of their own. The procedure is becoming increasingly common and in the USA accounts for 12 percent of all IVF treatments.