Second-hand smoke raises miscarriage risk

Active smoking in pregnancy has been associated with multiple adverse outcomes and some studies have also made associations between fetal loss and passive smoking at or around the time of conception or throughout the pregnancy. 

However, this is the first study to make an association with lifetime levels of second-hand smoke exposure and adverse outcomes in pregnancy.

Researchers in the US drew on historical data from 77, 805 postmenopausal women drawn from the Women’s Health Initiative Observational Study between 1993 and 1998, who had reported being pregnant at least once. 

Women were initially classified into ‘never-smokers’, or ‘ever-smokers’ during their reproductive years. The 40,850 women who identified themselves as ‘never-smokers’ were then further divided into groups depending on their years of exposure to second hand smoke in childhood and as adults in both the home and the workplace.