Risks remain for pregnant quitters

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.

"[Smoking] is like breathing in exhaust fumes, so of course it is going to affect a mother and foetus, but there are people who tell you their baby was fine even though they smoked throughout the pregnancy. I would say perhaps the placenta didn't implant as well as it could have or vessel growth wasn't as optimal as it could have been if they had been non-smokers."

The director of the Sydney South West Area Health Service's health promotion unit, Chris Rissel, said smoking rates among pregnant women were "unbelievably high" and health services needed to do more to help women beat their addiction.

"We need to make sure women are strongly advised against smoking every time they visit a health professional."

Nicotine replacement therapy was no longer contraindicated in pregnancy and a women's partner should be counselled to quit smoking in support, Associate Professor Rissel said.

- © Fairfax NZ News