Extensive new data from federal health officials confirm what other smaller studies have shown: Pregnant women who smoke are much more likely than nonsmokers to deliver low-birthweight babies.
Low birthweight, the National Center for Health Statistics points out, is the single most important predictor of infant mortality and has been linked to such other severe disabilities as mental retardation and cerebral palsy.
The national center last week released two reports that offer a mixed picture of infant health. While the provisional infant-mortality rate for 1991 dropped 2 percent, to 8.9 per 1,000 live births, the proportion of low-birthweight babies reached its highest level since 1978.
Federal health officials attributed much of the drop in infant-mortality rates in 1989 and 1990 to the introduction of new drugs that expand infants’ lung capacity to help treat respiratory-distress syndrome.
‘Don’t Smoke’
Teenage mothers, the data reveal, are especially prone to giving birth to undersized babies because they are more likely to smoke and to gain less than the recommended weight during their pregnancies, and they are also less likely to receive timely prenatal care.
Over all, 20 percent of women who gave birth in 1989 smoked, according to the report. And smokers are nearly twice as likely to have a low-birthweight infant, it noted.
The data also indicate that heavier smokers--those who smoked 1 to 2 packs a day--were two and a half times more likely to deliver undersized babies as nonsmokers.
“The message to all women who are pregnant or planning a family is quite clear: Don’t smoke,’' Secretary of Health and Human Services Louis W. Sullivan said in releasing the data. “The best thing you can do to help your baby is to forgo cigarettes.’'
The data on birth weights come from expanded birth certificates first used in 1989. For the first time, the certificates include information on mothers’ lifestyle and medical risk factors.
The revised certificates, which include questions on tobacco and alcohol use, weight gain, obstetric procedures, complications of labor and delivery, method of delivery, and abnormal conditions and congenital anomalies of the newborn, are significant because they offer additional information about the more than four million babies born each year in the United States.
“The data have been available in periodic surveys, but never on a large scale,’' said Stephanie Ventura, a senior analyst at the National Center for Health Statistics who wrote the report on the new birth-certificate data.
This initial report is just an introduction to the kind of studies that can be done now that similar national data will be available every year, Ms. Ventura said.
