A study of women who suffered miscarriages at 6 to 12 weeks of pregnancy found that they were more likely to have been exposed to secondhand smoke than those who did not have miscarriages during the same period, Reuters reported Sept. 20.

Swedish researchers tested blood cotinine levels -- a marker for secondhand-smoke exposure -- among 463 women who miscarried and 864 women who did not. They found that 24 percent of the women who suffered miscarriages were exposed to secondhand smoke, compared to 19 percent of the control group.

"Given the high prevalence of exposure to environmental tobacco smoke and the fact that spontaneous abortion is the most common adverse outcome of pregnancy, the public-health consequences of passive smoking regarding early fetal loss may be substantial," said the authors, led by Lena George of the Karolinska Institutet in Stockholm.

The researchers also found that women who smoked were twice as likely to miscarry as nonsmokers.

The study was published in the September 2006 issue of the journal Epidemiology.