NEW YORK, Aug 03 (Reuters) -- Women who quit smoking before or early in pregnancy not only have a healthier baby, they also have a rapid improvement in lung function themselves, a study suggests.
"Smoking cessation either before or at an early stage of pregnancy is associated with early, reversible increments of maternal airway function and (average) birth weights that are higher than among women who continue smoking," reported Dr. Tarun Das in the August issue of Obstetrics and Gynecology.
Das and colleagues at Laval University in Quebec looked at 40 ex-smokers, 175 nonsmokers, and 97 smokers who were pregnant. As many studies have found, the average weight of babies born to smokers was less than that of nonsmokers and ex-smokers.
The women who smoked during pregnancy had infants that weighed an average of 6.4 pounds at birth compared with 6.9 pounds in nonsmokers and 6.8 pounds in ex-smokers.
The researchers measured lung function in the women at about 21 weeks of pregnancy and found that ex-smokers and nonsmokers had significantly better lung function than current smokers. This was true even for women who quit smoking just 2 weeks before the test, the authors reported.
The rapid recovery of lung function after quitting smoking has been found in some, but not all studies of people in the general population who quit smoking. How quickly a person regains lung function after kicking the habit is probably related to how many cigarettes they smoked, and for how long, according to the report.
Hormonal changes associated with pregnancy may also play a role. "The improvement could also be influenced by the higher level of circulating progesterone during pregnancy," the authors wrote. Lung function generally increases during pregnancy due to such circulating hormones, however, the effect is "not sufficient to overcome the deleterious effects of cigarettes smoking on maternal airway function," according to the report.
The study provides new data "to support the potential beneficial effect of smoking cessation, both before and during early pregnancy," the authors conclude.
SOURCE: Obstetrics and Gynecology 1998;92:201-205.
