March 9, 2011 - To determine the risk of adverse fetal outcomes of secondhand smoke exposure in nonsmoking pregnant women. The analysis of 19 observational studies found a 23% increased risk of stillbirth with tobacco smoke exposure during pregnancy. And seven of the studies found that pregnant women exposed to second hand smoke were also 13% more likely give birth to a child with congenital malformations.
"Because the timing and mechanism of this effect is not clear, it is important to prevent secondhand smoke (shs, environmental tobacco smoke, ets, passive smoking, sidestream smoke, involuntary smoking) exposure in women before and during pregnancy," the group urged in their paper. Moreover it wasn't clear whether exposure to tobacco smoke toxins via the mother was the culprit, since active smoking by the father could damage genes in his sperm and impact the child as well, Leonardi-Bee's team noted. "These results highlight the importance of smoking prevention and cessation to focus on the father in addition to the mother during the preconception period and during pregnancy," they concluded in the paper.
PAPER: Secondhand Smoke and Adverse Fetal Outcomes in Nonsmoking Pregnant Women: A Meta-analysis, Jo Leonardi-Bee, PhD, MSc, John Britton, MD, MSc, FRCP, FFPH, Andrea Venn, PhD, MSc, Pediatrics published online 3/7/2011, ABSTRACT..
Previous data have shown that smoking during pregnancy boosts the risk of birth defects by 10% to 34% and stillbirth risk by 20% to 34%, so a modest impact of environmental exposure involving lower levels of the same tobacco smoke toxins wasn't surprising, the group noted.
Reference: Secondhand Smoke Risk Penetrates Womb by Crystal Phend, Senior Staff Writer, MedPage Today, 3/7/2011.