Light to moderate drinking during pregnancy can affect adolescent growth

  • Children with Fetal Alcohol Syndrome (FAS) commonly have growth deficits.
  • Growth deficits also exist among children prenatally exposed to alcohol but without FAS.
  • Researchers have found significant growth deficits among non-FAS children 14 years after birth.
  • The deficits have a dose-response relation to gestational exposure, and are evident at consumption levels less than one drink per day.

Growth deficits are common among children with Fetal Alcohol Syndrome (FAS), affecting their height, weight, and head circumference. Growth deficits have also been found among offspring exposed to alcohol during gestation but who have not developed FAS. Studies have, however, differed in this finding. Furthermore, few studies have followed offspring who were prenatally exposed to alcohol beyond their early and middle childhoods. A study in the October issue of Alcoholism: Clinical & Experimental Research examines the effects of alcohol exposure during gestation on the size of non-FAS offspring at 14 years of age.

“The Maternal Health Practices and Child Development Project began in 1982,” said Nancy L. Day, professor of psychiatry and epidemiology at the University of Pittsburgh School of Medicine and lead author of the study. “Its purpose has been to study the effects of prenatal exposure to alcohol, marijuana, tobacco, and other illicit drugs on the growth and development of the offspring. At numerous intervals, we have measured demographic status, the psychological, social, and household environment, maternal and paternal substance use, and substance use of the male partner in the household. We have also assessed the children's cognitive, behavioral, academic, and physical status. Furthermore, at ages 10, 14, and 16, we have additional measures of the children’s pubertal maturity, neuropsychological status, cognitive and behavioral development, affect, academic performance, psychiatric status, delinquent behaviors, substance use, and the substance use of their friends.”

For this study, part of the MHPCD project, women in their fourth month of pregnancy were recruited from an outpatient prenatal clinic between May 1983 and July 1985. The women were interviewed in their fourth month of pregnancy (n=1360), seventh month, and at delivery (n=763). The MHPCD project evaluated the women (or current caregiver) and their children at eight and 18 months, three, six, 10 and 14 years of age. Data for this study were gathered when the children (n=565) were 14 years of age.

“This study population represents a light to moderately exposed group of children and is in contrast to most studies that have recruited only heavily exposed subjects,” said Day. “The former group, however, represents the most common pattern of alcohol and other substance use during pregnancy.”

Despite only ‘light to moderate’ exposure, researchers identified significant growth deficits among the offspring. The adolescents were smaller in terms of their weight, height, head circumference, and skinfold thickness. Importantly, the growth deficits had a dose-response relation to gestational exposure and, furthermore, significant effects were found at consumption levels less than one drink per day. The researchers also evaluated the effects of pattern of use. They found that growth was affected by a continuous exposure to alcohol and not by concentrated or binge drinking. The frequency of heavy, or binge drinking (drinking four or more drinks/occasion), did not predict growth.

“It is notable that growth effects of prenatal alcohol can be detected in children more than 14 years after exposure,” said Sandra W. Jacobson, professor in the Department of Psychiatry and Behavioral Neurosciences at Wayne State University School of Medicine. “Moreover, the deficits were related to low-level alcohol exposure and a dichotomous measure of binge drinking during the first trimester, and were not found only among heavy drinkers or women who were alcoholic. The finding that growth effects can be related to first trimester drinking has very important implications for prevention and the need to identify women at risk earlier. Although the relatively small effects on head circumference and growth found at these low levels of exposure are unlikely to have any functional significance for the child, they suggest that there apparently was damage to the brain, particularly during sensitive fetal and early infant developmental periods. This damage may have serious implications for later cognitive and behavioral development.”

“There are two ways that a toxin such as alcohol can affect the developing fetus,” explained Day. “In a dose-response relation, there is a direct association between the amount of exposure and the size of the effect. Those with a small exposure will have very small growth deficits; those with a large exposure will have much larger growth deficits. In a threshold relation, a specific level of toxin must be present to affect the developing fetus. That is, exposure below the critical level will not have an effect, but exposure at or above that level will lead to the growth deficit. Our results have shown that the association between prenatal alcohol exposure and growth is one of dose-response. This is important for clinical and public health reasons because it means that even very small levels of alcohol exposure can affect the developing fetus. This means that there is no safe level for alcohol use during pregnancy. Women should abstain during these important months.”

Jacobson concurs. “However,” she said, “it is important to note that, although frequency of binge drinking was not statistically associated with reduced growth, the investigators reported that a dichotomous measure of bingeing was. Based on animal evidence, it is possible that these low level alcohol-related deficits may reflect maternal drinking on only a few days per week rather than drinking at very low levels every day. In our research, we have found that most women concentrate their drinking on one or two days per week and that the ‘average drinks per day’ measure may obscure that it is bingeing or a heavy drinking pattern in nonalcoholic, low-level drinking mothers that is negatively affecting their offspring.” Notwithstanding possible differences in interpretation, Jacobson lauds studies such as the one by Day and her colleagues.

“While most alcohol studies focus on alcoholism, often particularly in men,” she said, “studies of the effects of prenatal alcohol exposure provide a unique set of findings, including much needed new information on current drinking patterns of women of child-bearing age, including adolescents and mothers, as well as on the drinking patterns of socio-economically disadvantaged and minority women. These studies also provide critical human data, which can be used in conjunction with animal research findings to better understand the impact of prenatal use on alcohol brain and development.

Day plans to continue as director of the MHPCD project. “Our future plans include following the offspring in this cohort through young adulthood,” she said. “It is important to assess the effects of light and moderate exposure on the long-term development of these exposed individuals.”

Funding for this Addiction Science Made Easy project is provided by the Addiction Technology Transfer Center National Office, under the cooperative agreement from the Center for Substance Abuse Treatment of SAMHSA.

Articles were written based on the following published research:

Day, N.L., Leech, S.L., Richardson, G.A., Cornelius, M.D., Robles, N., Larkby, C. (October 2002). Prenatal alcohol exposure predicts continued deficits in offspring size at 14 years of age. Alcoholism: Clinical & Experimental Research, 26(10), 1584-1591.