ORLANDO – Maternal smoking has been associated with a number of serious respiratory and nonrespiratory infectious outcomes in infants, according to findings from two large case-control analyses.
Among 47,404 infants hospitalized for an infectious disease within 1 year of birth and 48,233 controls, and among 627 infants who died within 1 year of birth and 2,730 controls, maternal smoking was associated with both hospitalization because of to any infectious disease and mortality from any infectious disease (adjusted odds ratios, 1.52 and 1.51, respectively), Dr. Susanne Tanski of Dartmouth-Hitchcock Medical Center, Lebanon, N.H., reported at the annual meeting of the American Academy of Pediatrics.
Maternal smoking was associated with hospitalization due to a broad range of infectious diseases, including both respiratory and nonrespiratory diseases (adjusted OR, 1.69 and 1.27, respectively), said Dr. Tanski, who reported the findings of the subgroup analyses on behalf of lead study author Michael Metzger, Ph.D., and coauthor Dr. Abigail Halperin, both of the University of Washington, Seattle.
Stratification by birth weight and gestational age did not appreciably affect the findings with respect to morbidity risk in the infants of smoking mothers, which was found to be independent of both birth weight and gestational age. Mortality risk was found to be independent of gestational age, but the association among low birth weight infants was attenuated.
Even so, if an infant whose mother smoked was of normal weight and gestational age, exposure to maternal smoking appeared to carry an increased risk of infection as well as infectious disease mortality, Dr. Halperin said in an interview.
Included in the study were infants born in Washington from 1987 to 2004. The investigators reviewed linked birth certificate, death certificate, and hospital discharge records.
"We’ve known for a long time that babies born to mothers who smoke during pregnancy are at high risk for serious medical problems relating to low birth weight, premature delivery, and poor lung development, and while we have recognized respiratory infections as a common cause of these sometimes life-threatening infections, this study demonstrates that in utero exposure to smoke increases the risk of hospitalization and death from a much broader range of infections than previously documented," Dr. Halperin said.
She noted that the study was published earlier this year (Pediatr. Infect. Dis. 2013;32:e1-7 [doi:10.1097/INF.0b013e3182704bb5]) but received little notice. When the AAP invited her to submit an abstract for presentation at the conference, she said she was pleased to find that the paper was "selected for this honor."
"I’m very happy it’s receiving some attention now, because it is important to get this information out there so we can try to do something about it. We found that there was a dose-response effect related to number of cigarettes smoked per day, whereby smoking fewer cigarettes significantly lowered the risk for hospitalization," she said.
Thus, counseling pregnant women to reduce their smoking, even if they are not able to quit completely, may help reduce the impact of maternal smoking on infant outcomes, she said.
"Clinicians can help their patients stop smoking by providing nonjudgmental, positively framed advice to quit, and should strongly encourage pregnant women to quit smoking, both for their own health and for the health of their babies," she said, noting that women also should be counseled about the importance of protecting their children from secondhand smoke after birth, as secondhand smoke exposure increases the risk for many of the same infections seen in babies exposed in utero.
Evidence-based treatment, including counseling and approved cessation medication, should be offered to all patients who want to quit, regardless of whether or not they are pregnant, she added.
Dr. Tanski reported a having a patent pending and receiving royalties for a smoke sensor. Dr. Halperin and Mr. Metzger reported having no disclosures.