MedWire News: Pregnant women with pre-eclampsia are putting the lives of their unborn children, as well as their own lives, at risk if they continue to smoke during pregnancy, study results suggest.

Pre-eclampsia is a complication of pregnancy in which sufferers experience high blood pressure and protein in their urine. The condition reduces blood flow to the placenta, potentially causing harm to both the unborn child and the mother.

Lead researcher Dr Fiona Broughton Pipkin, from the University of Nottingham in the UK, explained: "Pre-eclampsia and eclampsia are the second most frequent cause of death in pregnancy in this country and cause an estimated 70,000 deaths worldwide among pregnant women each year.

"In 2005, 742 babies died as a direct result of pregnancy hypertension in England and Wales. Ten times this number are delivered prematurely for the same reason. They risk short-term breathing problems, potential brain damage and long-term cardiovascular disease. The deaths are the tip of an iceberg for hospital admissions and worry for mothers, babies and families."

To investigate whether smoking increases the pregnancy risks associated with pre-eclampsia further, Dr Broughton Pipkin and team studied data on more than 1000 pregnant European women with moderate-to-severe pre-eclampsia.

In total, 90 of the women continued to smoke during pregnancy, 71 gave up smoking after discovering that they were pregnant and the remainder had never smoked.

The researchers found that women who smoked during pregnancy were significantly more likely to give birth prematurely than those who did not smoke. Indeed, 35% of the smokers gave birth before 34 weeks' gestation, compared with 27% of the former smokers and 21% of those who had never smoked.

Furthermore, 46% of the women who smoked had babies of low birth weight, compared with 37% of former smokers and 28% of non-smokers.

Women who smoked also had a five-fold increased risk of developing full blown eclampsia compared with those who had never smoked.

"I feel very strongly that pregnant women should be encouraged as actively as possible to stop smoking, and this paper provides yet more reasons why," concluded Dr Broughton Pipkin.

Commenting on the findings, Ellen Mason, from the British Heart Foundation, said: "Research like this study is vital to help us understand the full effects of lifestyle choices on our heart and circulatory health and that of our children. Smoking is clearly potentially very harmful to mother and baby, and we need to support women in quitting at every stage of pregnancy."

The research appears in an advance online publication by the journal Hypertension.