Thursday 21st August 2008
Women who quit smoking during their first pregnancy still have a higher risk of giving birth to small or premature babies, even if their second baby is born three years after they have given up cigarettes, researchers have found.
The study, of more than 244,000 mothers across NSW, sheds new light on the lasting effects of smoking and has prompted health experts to plead that all prospective mothers quit.
The chemicals in cigarettes, such as carbon monoxide, affect a placenta's ability to implant properly on the uterine wall, inhibit blood flow to the foetus and reduce the body's ability to make collagen, which weakens amniotic membranes, increasing the risk of a baby being born early, small or dying before birth.
The study, to be published today in the British Journal Of Obstetrics And Gynaecology, found that once a woman had one premature birth, the risk of a second baby also being born prematurely increased by up to 28 per cent, while women who had a small first baby were 4.7 times more likely to have a small second baby.
Quitting smoking after the first baby reduced the risk, but did not eliminate it, the study found.
About one in five women admits to smoking during pregnancy, although the real figure was probably significantly higher, an associate professor in foetal medicine at Liverpool Hospital, John Smoleniec, said yesterday.
"A patient will always tell you they smoke less than they do because they feel guilty as soon as you ask," Associate Professor Smoleniec said.