WHITE PLAINS, N.Y., JAN. 9, 2002 - Why do some women who smoke cigarettes during pregnancy have low birthweight babies while others do not? Until now the answer has largely been a medical mystery. Now, for the first time, a team of scientists funded in part by the March of Dimes has found part of the answer in how certain key genes interact with cigarette smoke.
The research was published today in the Journal of the American Medical Association.
Xiaobin Wang, M.D., M.P.H., Sc.D., of the Department of Pediatrics, Boston University School of Medicine, and colleagues reported their finding that pregnant women who smoke are much more likely to have a premature or low birthweight baby if two genes that normally control the body's chemical modification of components of cigarette smoke were missing or inactive. The authors also note that 65 percent of all infant deaths in the United States occur among low birthweight infants (5.5 pounds or less).
"This is the first study to demonstrate a link between cigarette smoking, specific genes, and low birthweight," said Nancy S. Green, M.D., acting medical director of the March of Dimes. "Although this finding needs to be confirmed, it is solid, innovative science and we hope it will lead to better ways to recognize and treat those women at high risk of having a low birthweight baby. For example, in the future, smoking prevention or cessation could be more strenuously targeted to those women with this genetic profile."
With support from the March of Dimes, Dr. Wang is seeking to identify specific genetic traits that make women more likely to give birth to a low birthweight or premature baby. She has chosen 51 genes to study, including those involved in the body's responses to stress and infection, in hormonal changes related to pregnancy, and in ways in which the body handles a wide variety of environmental toxins.
In an effort to reduce the high number of preterm births that continue to plague the United States, the March of Dimes has awarded nearly $8 million in grants to investigate biological and environmental factors that may contribute to the more than 450,000 preterm or low birthweight births each year. As part of this unique research program, the March of Dimes selected Dr. Wang as one of six prominent investigators in the area of preterm birth to receive March of Dimes Perinatal Epidemiological Research Initiative (PERI) grants.
Dr. Wang and her colleagues studied 741 pregnant women who gave birth at Boston Medical Center during 1998-2000. The lowest birthweights and shortest gestations were seen in babies of those women who smoked throughout pregnancy and had variant forms of both genes on which the study focused, known as CYP1A1 and GSTTI. Among women who had never smoked, there was no independent increased risk of low birthweight or prematurity from the same genetic variations.
"Maternal Cigarette Smoking, Metabolic Gene Polymorphism, and Infant Birth Weight," by Wang et al. was published in the Journal of the American Medical Association, volume 287, number 2, January 9, 2002.
The March of Dimes is a national voluntary health agency whose mission is to improve the health of babies by preventing birth defects and infant mortality. Founded in 1938, the March of Dimes funds programs of research, community services, education, and advocacy to save babies. For more information, visit the March of Dimes Web site at www.marchofdimes.com, its Spanish Web site at www.nacersano.org, or call 1-888-MODIMES.