A study conducted at the University of Wisconsin-Madison's Harlow Primate Laboratory demonstrates for the first time in a laboratory setting that even moderate drinking can harm infant development.
Results of the study, published in the October issue of the journal Child Development, show that moderate exposure to alcohol in pregnant rhesus monkeys produced a number of deficits in the infants, including reduced motor skills, shorter attention span and increased drowsiness. Moreover, a combination of alcohol and mild psychological stress on the pregnant mothers compounded some of the symptoms.
Mary Schneider, a UW-Madison occupational therapy professor and principal investigator of the study, says the study is the first attempt to look at the potential health effects of social drinking during pregnancy, using both a controlled laboratory setting and species very close to humans.
Previous studies involving humans reached similar conclusions, but could not factor out other variables, such as environment, other drug use and socio-economic status, that affect infant health, she says.
Most research has focused on fetal alcohol syndrome, a lifelong condition that can cause mental retardation and other behavioral and learning problems. That condition stems from excessive drinking during pregnancy, but Schneider says her study shows the risks are not limited to problem drinkers.
"It seems to contradict a common assumption that 'anything in moderation' is fine," she says. "We hope that doctors and educators will take this to heart and further encourage women to limit alcohol and minimize stress during pregnancy."
The study included 33 pregnant rhesus monkeys that were placed in one of three study groups: One group consumed alcohol daily beginning five days prior to breeding; a second group was exposed to both alcohol and mild stress; and a third control group consumed a solution with no alcohol.
The alcohol dosage was comparable to one or two drinks daily for humans, producing a blood alcohol content of .02 to .05. The mild stress was produced by exposing the monkeys to three short bursts of noise when they were placed in an unfamiliar environment.
After birth, the infants were given a series of physical and behavioral tests that assess infant development, and provide a way to measure characteristics such as attention, neuromotor skills and temperament.
The infants from all three groups were physically normal, Schneider says. However, impairments in the alcohol-exposed infants included poor motor maturity, shorter attention spans and increased drowsiness. Of the pregnant monkeys that were exposed to both alcohol and mild stress, the males were born with low birth weight. The motor impairments of monkeys in that group also were more severe.
The study was funded by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and the W.T. Grant Foundation. Dr. Enoch Gordis, director of NIAAA, says Schneider's study takes a big step toward verifying the dangers of moderate drinking during pregnancy.
"This is an important paper, probably the first primate fetal alcohol syndrome project that offers a true moderate drinking model," Dr. Gordis says. "With Dr. Schneider's monkeys, we have all the advantages of animal model control. And among animal models, the primate model is important because primates permit a level of cognitive testing far closer to human behavior than is possible with, for example, rodents."
Despite a growing awareness of fetal alcohol syndrome, drinking during pregnancy remains a major health hazard in the United States. A 1995 phone survey by the Centers for Disease Control and Prevention found that 3.5 percent of 1,313 pregnant women surveyed admitted to having seven or more drinks per week or binged on five or more drinks on a single occasion in the preceding month. That was up from 0.8 percent in 1991. The sample suggested that 140,000 pregnant women nationally were frequent drinkers in that year.
"With so many children born every year having been exposed to alcohol, these results might help explain why we are seeing more and more problems in children when they reach school age and adolescence," Schneider says.