While it's no secret that pregnant women should steer clear of nicotine and smoking, a new study suggests that the consequences may be more serious than previously thought. Researchers at the University of Washington have found that babies whose mothers smoke during pregnancy are at greater risk of being hospitalized or killed by a wide spectrum of infections — respiratory as well as non-respiratory. In a survey of existing data, children exposed to smoke during gestation were 50 percent more likely to develop these health complications than children with non-smoking mothers.

The study, which is to be presented at the American Academy of Pediatrics on Oct. 27, incorporates material from a 2013 survey published in the Pediatric Infectious Disease Journal. Both research efforts involved reviews of hospitalization records and death certificates of infants born in the state of Washington between 1987 and 2004. According to lead researcher Abigail Halperin, the results suggested that exposure to smoke during gestation was associated with a number of health risks not yet accounted for in scientific literature.

"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," she said in a press release. "While respiratory infections have been recognized as a common cause of these sometimes life-threatening illnesses, this study shows that babies exposed to smoke in utero also have increased risk for hospitalization and death from a much broader range of infections — both respiratory and non-respiratory — than we knew before."

The link between smoking during pregnancy and postnatal complications persisted when the researchers controlled for factors like birth weight and gestational age. Even full-term babies with healthy birth weights were at significantly greater risk of hospitalization and death if their mothers smoked throughout the pregnancy. According to Halperin, this suggests that exposure to smoke during gestation may impair the child’s immune system.

That said, the team also found that pregnant smokers can reduce these risks by cutting back or quitting partway through their term. For this reason, prenatal care programs may benefit from incorporating anti-smoking information and counseling.

“Counseling pregnant women to reduce their smoking, if they are not able to quit completely, may help reduce infant hospitalizations or death," Halperin added.

Source: Metzger MJ, Halperin AC, Manhart LE, Stephen HE. Association of Maternal Smoking During Pregnancy With Infant Hospitalization and Mortality Due to Infectious Diseases. Pediatric Infectious Disease Journal. 2013.