Smoking pregnancy risks are cumulative, researchers say

The more cigarettes women smoke during their reproductive years, the higher the risks of pregnancy complications, new research shows.

The same is true for passive smokers, with those who are regularly exposed to the smoke of others more likely to suffer miscarriages and stillbirths than those who only occasionally inhale smoke from the cigarettes used by friends, colleagues and relatives.

Researchers from a number of universities analysed the historical data of over 80,000 American women in an attempt to better understand the links between tobacco consumption and pregnancy, reports.

According to the results, those who are active smokers during their childbearing years are 16 per cent more likely to suffer miscarriages than those who don't smoke at all. Long periods (more than a decade) of regular exposure to second-hand smoke also heightened the risk by 17 per cent.

The authors of the report, which was published in the Tobacco Control journal, were quoted by as saying: "In this study, active smoking was associated with spontaneous abortion (miscarriage), stillbirth and tubal ectopic pregnancy with a significant dose-response trend.

"Second-hand exposure to never-smoking women at the highest levels was also associated with all three adverse pregnancy outcomes with significant dose-response trends."

Long-term passive smokers are also 55 per cent more likely to give birth to a stillborn child, with the risk just 44 per cent higher for those who smoke directly.