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Cigarette risk to babies higher 10-year study urges sterner warnings to pregnant women Wednesday, June 03, 1998 By Michael Woods, Post-Gazette Washington Bureau
WASHINGTON -- Pregnant women who smoke cigarettes risk more serious damage to their unborn and newborn infants than previously believed, a 10-year review of scientific research concluded yesterday.
A 10-year review of scientific research by Dr. Theodore Slotkin, a national authority on drugs at Duke University, suggests that "cigarette" babies not only run a risk of being born prematurely and underweight, but face a higher risk of crib death and subtle brain damage resulting in learning disabilities, hyperactivity and behavioral problems.
Cigarette smoking in pregnancy may cause 100,000 fetal deaths each year, he reported, but one in four American women continue to smoke during pregnancy.
Slotkin's report, published in the June edition of the Journal of Pharmacology and Experimental Therapeutics, summarizes more than a decade of research on fetal nicotine exposure in pregnant laboratory rats.
In an interview, Slotkin contended that the U.S. surgeon general's warning label on cigarette packs, which now addresses premature births and underweight infants, should be expanded to inform pregnant women about smoking's newly identified dangers.
Taken in sum, cigarette babies are a more serious society-wide problem than crack babies, born to pregnant women who use cocaine, or fetal alcohol syndrome, a group of birth defects caused by excessive alcohol use during pregnancy.
Yet Slotkin said that both crack babies and those with fetal alcohol syndrome had received much more public attention, and emphasis from medical professionals and government agencies, than cigarette babies.
"We should get smoking and pregnancy the same kind of public awareness as crack baby syndrome, which is much less prevalent and which has not been found to cause the kinds of damage seen with cigarette smoking in pregnancy," he said.
Contrary to popular belief, most women who smoke don't quit during pregnancy, he added. Studies based on what women say conclude that 50 percent stop. Urine or blood tests, however, show that only small numbers really do stop.
In his experiments, pregnant lab rats were rigged with implantable minipumps to infuse precise doses of nicotine into the blood. The technique simulated human nicotine exposures that would result from smoking from one-half to two packs of cigarettes daily.
The technique isolated nicotine's effects by eliminating factors that blurred previous studies in humans. Women who smoke during pregnancy often are poor, get less prenatal care, may consume excess alcohol and abuse other drugs. Researchers could not separate nicotine's effects from those of the other factors.
Slotkin said the experiments demonstrated conclusively that nicotine caused fetal deaths and brain cell damage.
"The conclusion is inescapable that smoking itself is responsible for tens of thousands of perinatal deaths and for like numbers of infants whose disabilities may range from outright brain damage to subtle cognitive defects."
Indeed, researchers now suspect that many harmful effects apparent in crack babies actually are due to nicotine. Slotkin said many women who use cocaine during pregnancy also smoke cigarettes. Until now, researchers could not isolate the effects of cigarettes.
The animal studies demonstrate that nicotine kills brain cells outright, he said. Nicotine also interferes with "wiring" of the brain, the process in which rapidly growing brain cells establish interconnections critical for normal brain function.
Nicotine also damages nerve cells outside the brain in ways that cause premature loss of a mechanism that helps infants survive during periods of reduced oxygen supply. These occur during birth itself and during sleep.
Normal infants respond with increased breathing and faster heart rate. Cigarette babies don't, and are predisposed to crib death or sudden infant death syndrome.
The studies show that nicotine, unlike many other chemicals that harm the fetus, does most of its damage after the first three months of pregnancy. Pregnant women thus have a "window of opportunity" in the first three months of pregnancy to quit smoking.
Slotkin advised much more caution in use of skin patches, chewing gum and other nicotine replacement therapy. Patches and other replacement therapy are sold without a prescription, and pregnant women are urged to be cautious in use of the devices.
Women should make every effort to stop all use of nicotine from cigarettes or replacement therapy in the first three months of pregnancy, he advised. Those who cannot stop smoking should get the lowest possible dose of nicotine replacement, and should never smoke at the same time.
Gum or inhalers, which deliver less nicotine than skin patches, may be the best approach, he said. Pregnant women, including those in their first three months, also should remove the patch at night, allowing drug levels to decline in the fetus. The drop may reduce damage to fetal brain cells.
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