A new study adds more evidence to the case that even secondhand smoke can harm unborn babies and could lead to a higher risk of having a stillbirth.
Canadian researchers also found that newborns weighed less and had smaller heads if their mothers were passive smokers.
“This information is important for women, their families and healthcare providers,” Dr. Joan Crane of Eastern Health in St. John’s and colleagues wrote in the BJOG: An International Journal of Obstetrics and Gynecology.
Secondhand smoke is thought to expose people to about one percent of the smoke that active smokers inhale.
According to the researchers, “undiluted side-stream smoke contains many harmful chemicals and in greater concentration than cigarette smoke inhaled through a filter.”
Those chemicals may harm the fetus by restricting blood flow and possibly damaging the placenta.
The researchers used a database of pregnant women from the Canadian provinces of Newfoundland and Labrador to shed light on the question.
They also looked at other birth outcomes, like head circumference.
Eleven percent of the 12,000 women in the database said they had been exposed to second hand smoke.
The rate of stillbirth was 0.83 percent in passive smokers and 0.37 percent in women who did not breathe tobacco fumes.
The researchers accounted for several risk factors as well, including age and the women’s drinking and drug habits. When these factors were accounted for, passive smokers had over three times the odds of stillbirth.
“This is huge,” Dr. Hamisu Salihu, an expert on stillbirth at the University of South Florida in Tampa, told Reuters. “We can now inform patients that exposure to secondhand smoke means they can lose their baby.”
The researchers also found that babies born to passive smokers weighed nearly 2 ounces less than babies whose mothers lived and worked in smoke-free households.
According to the study, the babies’ heads were an average of about 0.1 inch less as well.
“Policy makers should really take this matter seriously,” he told Reuters. “We need to enact laws to protect these babies.”
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