Both parents can pass on risk of pre-eclampsia

Men and women born following a pregnancy affected by pre-eclampsia can both pass an increased risk of the condition on to the next generation, a Norwegian study has found. Scientists at the University of Bergen used data from the country's birth registry to show that daughters of women affected by pre-eclampsia have more than double the usual risk of developing the condition themselves. The team, who published their findings early online in the British Medical Journal, also found that men born to women with pre-eclampsia have a moderately increased risk (around 50 per cent) of fathering an affected pregnancy.

Pre-eclampsia affects around 3-5 per cent of pregnant women, and usually arises during the second half of pregnancy. It can cause high blood pressure, liver problems, blood abnormalities, slow fetal growth and, if untreated, can lead to life-threatening seizures in the mother. Because the only way to 'treat' pre-eclampsia is to deliver the baby, the condition is a major reason for premature births and their associated health problems. The causes of pre-eclampsia are unknown, although some scientists think that it could be triggered by the mother's immune system attacking the fetal cells that form the placenta. The condition runs in families, suggesting that genes are involved, but other factors are also thought to play a role.

In the latest study, the researchers used data from the medical birth registry of Norway from 1967-2003 to investigate the recurrence of pre-eclampsia across generations. They analysed results from 438,597 singleton babies born to 238,617 women, and 286,945 singleton babies fathered by 158,340 men. The scientists found that women whose mothers had pre-eclampsia have a 2.2-fold increased risk of being affected by the condition during their own pregnancies, while men born to women with the condition have a 1.5-fold increased risk of fathering an affected pregnancy.

Study author Rolv Skjaerven said that the findings support the theory that both the mother's and father's genes contribute to the risk of pre-eclampsia. 'The risk through affected mothers is higher because they carry their mother's susceptibility genes and also transmit independent genetic risk factors to their unborn child', he said, adding that 'the risk through affected fathers is lower because fathers transmit only fetal risk genes'.

Mike Rich, of the UK charity Action on Pre-eclampsia, stressed that many factors are involved in the condition. 'We have known for a while family history increases the risk, but so does being obese and being over 40', he told BBC News Online. Earlier this year, Dutch scientists reported the identification of a gene, called STOX1, that appears to be linked to the onset of the condition in some families.