A new federal law requiring warning labels on all alcoholic beverages will make millions more men and women aware that consuming alcohol can cause serious damage to a developing baby, says a local official of the American Academy of Pediatrics.

"The causes of most birth defects are unknown. But one leading known cause, and the major preventable one, is fetal alcohol syndrome," Dr. Claire O. Leonard, associate professor of pediatrics at the University of Utah Medical Center and a member of the academy's Committee on Genetics, told the Deseret News."Although we must continue more comprehensive education efforts about the many dangers of alcohol abuse, the new warning labels are a significant step."

By December 1989, all containers of beer, wine and liquor will for the first time be required to bear a warning label that carries two messages.

It will read: "GOVERNMENT WARNING: According to the Surgeon General, women should not drink alcoholic beverages during pregnancy because of the risk of birth defects. Consumption of alcoholic beverages impairs your ability to drive a car or operate machinery, and may cause other health problems."

Although similar warning-label legislation has been considered by Congress for more than a decade, the new requirement was included in the Omnibus Drug Bill passed Oct. 21. The bill's co-sponsor was Sen. Orrin Hatch, R-Utah.

"The labels, besides warning of the dangers of alcohol, remind those who read them about the importance of fighting alcohol and drug abuse. For many people, and especially those who are label conscious, these warning labels can be a point of decision against the use of alcohol," said Hatch, who has lobbied for the warning labels for the past 10 years.

"A warning label educates while allowing citizens the freedom to choose. Therefore, the consumer is more knowledgeable and responsible for his or her actions."

The Legislature has also on many occasions called on Congress to enact such legislation. Hatch said President Reagan is expected to sign the bill into law.

The law, Leonard says, will help address a pressing health concern.

More than 5,000 babies born in the United States each year suffer from fetal alcohol syndrome, which can occur when pregnant women drink. As many as 50,000 newborns may suffer from a less understood condition and milder form of alcohol-related birth defects known as fetal alcohol effects.

Leonard said fetal alcohol syndrome is characterized by a cluster of abnormalities including prenatal and postnatal growth deficiency; facial malformations, including a small head circumference, small eyes and flattened midface. Other characteristics are a sunken nasal bridge and a long smooth upper lip; central nervous system dysfunction; and varying degrees of major organ-system malformations.

"The brain, size and growth of the child are clearly affected by fetal alcohol syndrome, and congenital heart disease is increased. There are also minor skeletal problems, as well as the facial features described. But it's not what most people think of as a facial birth defect," Leonard said.

Because the syndrome doesn't cause the child to look grossly deformed, the specialist said many women are not frightened enough to stop drinking before or during pregnancy.

"But one of the greatest concerns is the effect of alcohol on the developing fetal brain," Leonard stressed. "Many children have speech and learning problems, and even retardation as a result of fetal alcohol syndrome."

Leonard said one of the first specialists to call attention to the effects of fetal alcohol syndrome was Dr. Kenneth L. Jones, director of the California Teratogen-Registry, which focuses its attention on agents harmful to unborn children.

Recent studies conducted by Jones link an average of one to two drinks daily to decreased birth weight, growth abnormalities and behavioral problems in the newborn and infant. Increased risk of spontaneous abortion has been found at an even lower consumption of one to two drinks, twice weekly.

"But there is no established safe dose of alcohol during pregnancy, nor does there appear to be a safe time to drink," Leonard said. "Many women drink before they realize they are pregnant, yet early pregnancy is the most sensitive time."

Leonard warns that alcohol is a poison and women should not drink during the child-bearing years because they have to realize they could become pregnant at any time.

"Most women are pregnant for several weeks before they realize the pregnancy exists," she said. "Yet that is a very sensitive time of development for the fetus."

Leonard acknowledges that whenever drinking is stopped during pregnancy, the risk of alcohol effects and consequences of alcohol exposure are decreased. Although there is no information about the effects of a rare social drink, women who are concerned about their drinking habits and would like additional information or a referral to a physician, can call the Pregnancy Risk Line at 583-2229 or 1-800-822-2229.