Pregnant women who do not smoke may still suffer from the unwanted consequences of smoking. Researchers from China have found that nonsmoking women who were exposed to secondhand smoke during their childhood may have elevated risk of a miscarriage.
Smoking And Miscarriage Risk
Earlier studies have found a link between smoking and the risk of pregancy loss. In a 2010 study involving 1,300 Japanese women, for instance, researchers found that pregnant women who smoked heavily early in their pregnancy are more than twice as likely than their nonsmoking counterparts to suffer a miscarriage during the first trimester of pregnancy.
Miscarriage Risk In Nonsmoking Women Exposed To Secondhand Smoke
Findings of the new study, which were published in Tobacco Control on Dec. 23, showed that exposure to secondhand smoke also poses a risk to pregnant women even if their exposure to tobacco smoke happened when they were still a child.
For the new study, Shanshan Yang, from the Institute of Geriatrics at the Chinese PLA General Hospital in China, and colleagues looked at the survey data of nearly 20,000 Chinese women who were at least 50 years old.
Although the women involved in the study had never been smokers, the researchers found that those who lived with two or more smokers before they reached 18 years of age had a 20 percent increased risk of miscarriage.
The participants who were exposed to secondhand smoke at least five times per week were likewise found to have a 14 percent greater risk of losing a pregnancy than the women who were not exposed to secondhand smoke when they were a child.
The women who grew up in homes with only one smoker, or who had been exposed to smoke less than five times per week, however, did not appear to have any changes in miscarriage risk.
"We used baseline data of the Guangzhou Biobank Cohort Study (GBCS) to examine the association of childhood secondhand smoke (SHS) exposure with a history of pregnancy loss," the researchers wrote in their study. "Childhood SHS exposure was associated with higher risks of pregnancy loss in middle-aged and older Chinese women."
Limitations Of The Study
The study, however, had some limitations. For one, the participants needed to rely on their memories of childhood and the researchers were not able to assess the age when the women had their miscarriage. The researchers were not also able to determine if the women were exposed to secondhand smoke when they were pregnant, which could have also boosted their risk of losing pregnancy.
Nonetheless, the researchers said that the study result supports the enactment of stronger national smoke-free laws and the promotion of smoke-free homes to protect children. They also noted of a need for campaigns that can change the social norms associated with smoking and passive smoking.
Other Risk Factors For Miscarriage
Besides smoking, other risk factors that may increase a woman's likelihood to suffer from miscarriage include drinking too much alcohol, chronic conditions like diabetes, weight problems such as obesity, and even the use of yeast infection drugs while pregnant.