March 7, 2011 -- Pregnant women who don’t smoke but breathe the secondhand smoke of others have an increased risk for delivering stillborn babies or babies with birth defects, according to a new research review.
Children born to women who smoke during pregnancy have an increased risk for fetal death, premature birth, low birth weight, and birth defects.
Secondhand smoke exposure has been linked to lower birth weight, but it has not been clear if exposure during pregnancy influences other birth outcomes in nonsmoking women.
In an effort to better understand the relationship, researchers from the University of Nottingham in the U.K. analyzed 19 studies that examined birth outcomes among nonsmoking women exposed to tobacco smoke during pregnancy.
The data showed a 23% increase in the risk of stillbirth associated with passive smoke exposure and a 13% increase in the risk of birth defects.
The analysis, which appears in the April issue of Pediatrics, failed to show a relationship between secondhand smoke exposure and miscarriage before 20 weeks of gestation or death around the time of birth.
“I think we can confidently say from this analysis that secondhand smoke exposure during pregnancy increases the risk for stillbirth and delivering a baby with congenital malformations,” says study researcher Jo Leonardi-Bee, PhD, of the U.K. Center for Tobacco Control Studies at the University of Nottingham. “These findings confirm the importance of avoiding such exposures, both in the home and in public places.”
By one estimate, 126 million nonsmokers in the U.S. are regularly exposed to secondhand smoke.
Leonardi-Bee says the home remains the biggest source of secondhand smoke exposure for most nonsmoking women.
“Smoking bans have certainly reduced exposures in public places and in work settings, but, of course, they don’t address the problem of home exposure,” she says.
Pediatrician Jonathan P. Winickoff, MD, of Harvard Medical School, researches the effects of secondhand cigarette smoke exposure on babies and children. He tells WebMD that smoking during pregnancy is the No. 1 preventable cause of low birth weight and neonatal intensive care (NICU) admissions.