Numerous studies have reported that secondhand smoke is harmful to one’s health. A new study has reported that a woman’s exposure to secondhand smoke both during and before a pregnancy could result in the loss of her fetus. The findings were published online on February 26 in the journal Tobacco Control by researchers at the Roswell Cancer Institute and the University at Buffalo in Buffalo, New York.
The study found that pregnant women who never smoked had an increased risk of losing their pregnancy if exposed to secondhand smoke. The study authors note that previous studies have reported that smoking during pregnancy was associated with the three adverse pregnancy outcomes that their study evaluated: spontaneous abortion (miscarriage; loss of a fetus before 20 weeks of gestation), stillbirth (loss of a fetus after 20 or more weeks of gestation), and a tubal pregnancy. However, studies evaluating the effects of secondhand smoke are limited. Therefore, the new study assessed two important factors; (1) it evaluated lifetime secondhand smoke exposure rather than only during pregnancy or reproductive years, taking into consideration smoke exposure in participants’ childhood and adult years; (2) the comparison group of never-smokers was limited to women without any secondhand smoke exposure, which allowed for a truer control group compared to previous studies.
The study group comprised 80,762 women who were enrolled in the Women’s Health Initiative Observational Study. The authors noted that the large sample size and comprehensive assessment of secondhand smoke exposure strengthened the findings of the study. They evaluated historical reproductive data, current and former smoking status, and details regarding secondhand smoke exposure among the study group. The women came from a wide range of geographic areas and had multiple ethnic, educational and socio-economic backgrounds. Thus, this allowed for a comprehensive assessment of detailed information on exposures, outcomes and potential confounders (factors that could compromise the data).
The researchers found that women with the highest levels of secondhand smoke exposure, despite never having smoked themselves, had a significantly greater risk for all three adverse pregnancy outcomes; furthermore, these risks approached the risk among women who smoke (those who smoked more than 100 cigarettes in their lifetime). The highest levels of lifetime secondhand smoke exposure were among women who experienced childhood exposure for more than 10 years, adult home exposure for more than 20 years, and adult work exposure for more than 10 years.
“This study offers new information for women regarding the lifetime impact secondhand smoke can have on reproductive outcomes and their ability to successfully bring a pregnancy to full term,” says Dr. Hyland. “The strength of the study also provides public-health professionals and others with information upon which to base health guidelines about the significant consequences of secondhand smoke.”
Take home message:
This study notes that secondhand smoke exposure to a woman at any age increases the risk of an adverse pregnancy outcome. It provides yet another reason not to expose others to secondhand smoke, and yet another reason not to smoke.