Fetal alcohol spectrum disorders may be more widespread in U.S. communities than previously thought, an observational study of 6,600 first-graders suggests.
The active-case ascertainment study, online in JAMA, estimates the prevalence of fetal alcohol spectrum disorders at 1.1% to 5%, reported Christina Chambers, PhD, MPH, of the University of California San Diego, and coauthors
Weighted, those numbers jump to a range of 3.1-9.8% — considerably higher than previous prevalence estimates of about 1%.
“We’ve had spotty estimates of the prevalence of fetal alcohol spectrum disorders in the U.S.,” Chambers told MedPage Today. “It is difficult to recognize, so it can be hidden. There may be a stigma associated with it and reluctance on the part of mothers to be forthcoming about alcohol exposure, and on the part of physicians to ask about it.”
Fetal alcohol spectrum disorders involve central nervous system damage and physical deficits that stem from prenatal alcohol exposure. The previously accepted prevalence estimate was derived largely from clinic-based studies and passive record surveillance.
Active-case ascertainment — in which investigators pull data from many sources including site visits — has been used in other countries and has led to higher prevalence estimates, Chambers explained.
Her group’s study evaluated children at four sites in Midwest, Southeast, Pacific Southwest, and Rocky Mountain communities where primary investigators had developed trust. The researchers sampled first-grade students in public and private schools for 2 academic years from 2010 to 2016. Sampling methods and consenting processes varied across sites.
Consent rates for screening among eligible children ranged from 36.9% to 92.5% and averaged 59.9%. From a population of 13,146 first graders, 6,639 children participated; 51.9% were boys and 79.3% were of white maternal race.
The researchers screened children for growth, and parents for concerns about child development. A dysmorphologist studied the facial features of children who screened positive; neurobehavioral tests were given to the students; and the mothers were interviewed about lifestyle factors and prenatal alcohol exposure.
The team investigated 222 cases of fetal alcohol spectrum disorders in the group. Conservative prevalence estimates ranged from 11.3 (95% CI 7.8-15.8) to 50.0 (95% CI 39.9-61.7) per 1,000 children. Weighted prevalence estimates ranged from 31.1 (95% CI 16.1-54.0) to 98.5 (95% CI 57.5-139.5) per 1,000 children.
Weighted estimates were substantially higher than conservative ones because the denominators were restricted to children who had received a full evaluation.
“The conservative estimates assume that every child who didn’t participate in the study didn’t have fetal alcohol spectrum disorder,” Chambers said. “The flip side of the coin says that instead of the denominator being all eligible children, it is only those children for whom we had sufficient information to classify them — a much smaller number.
“Of course, we don’t know whether mothers who agreed to participate were more likely to have affected children or the opposite — that mothers who agreed to participate were less concerned and those who may have had an affected child might shy away from consenting,” she added.
The restricted denominators represented 19-50% of the larger number of eligible children used as denominators for conservative estimates. Of the 222 children identified, 27 met criteria for fetal alcohol syndrome, 104 for partial fetal alcohol syndrome, and 91 for alcohol-related neuro-developmental disorder.
The results showed that while many parents and guardians were aware of their children’s learning and behavioral challenges, only two of the 222 children had been diagnosed previously with fetal alcohol syndrome disorders.
Prevalence varied by sample, site, and sampling method: 11.3 per 1,000 children in a Midwestern sample, and 50 in a Rocky Mountain sample. Weighted prevalence ranged from 31.1 per 1,000 children in a Southeast sample to 98.5 in a Rocky Mountain sample.
Writing in an accompanying editorial, Shannon Lange, MPH, of the Center for Addiction and Mental Health in Toronto, and colleagues, said that these figures “demonstrate the need to establish a national fetal alcohol spectrum disorders surveillance system to monitor its prevalence, as well as the prevalence of its main indicator — alcohol use during pregnancy — regularly and systematically over time.”
“Despite the Surgeon General’s recommendation, we’re not seeing a decline in risky drinking in women of reproductive age,” Chambers observed. “In fact, there’s some evidence of increased risky drinking in women in that age category. It really does behoove physicians to realize this is extremely important — to ask a woman about her pattern of drinking and potential for becoming pregnant, before she ever gets pregnant. And once she is pregnant, to have a clear message that avoiding alcohol entirely is the best approach.
“The pushback is always that we can’t be sure a couple of drinks a week will have any effect on a child,” Chambers added. “But the recommendation to avoid it entirely is based on the idea that there are differences in susceptibility. We don’t know what a safe threshold is.”
Fetal alcohol spectrum disorders often are inter-generational, with a high rate of familial recurrence, Lange and colleagues wrote, and some women may need support to reduce the likelihood of bearing more affected children.
Chambers et al noted several limitations to their study, including that the results might be biased by the characteristics of the families who agreed to participate in the study, and that neurobehavioral testing of first-graders might miss children whose deficits would not appear until later.
In addition, the four communities also may not be representative of the United States overall. Variability in prevalence estimates across sites may be due to the low number of children classified in each fetal alcohol spectrum disorder category, but also could reflect the diversity that exists elsewhere, much like the variability in risky alcohol consumption reported among U.S. women, the researchers noted.
The study was funded by the National Institute on Alcohol Abuse and Alcoholism.
The researchers and the editorialists reported having no conflicts of interest.