Although drinking during pregnancy has long been considered taboo, new research suggests that at least 1 in 20 U.S. children may have health or behavioural problems related to pre-birth alcohol exposure.The study found that between 2.4 percent and 4.8 percent of children have some kind of foetal alcohol spectrum disorder, or FASD.
"Knowing not to drink during pregnancy and not doing so are two different things," especially before a woman knows she is pregnant, said lead researcher Philip May, a professor of public health at the University of North Carolina at Chapel Hill.
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He said the high prevalence of children affected by drinking during pregnancy may be due to social pressures or women's difficulty in changing their drinking habits.
Findings from the study were reported online in the print issue of Paediatrics.
Foetal alcohol spectrum disorders include foetal alcohol syndrome disorder plus other conditions that include some, but not all, of the characteristics of foetal alcohol syndrome, according to background information in the study.
Foetal alcohol syndrome is the most severe end of the spectrum, and children with this condition have abnormal facial features, structural brain abnormalities, growth problems and behavioural issues. Children on the less severe end of the spectrum may have impairments in the ability to complete tasks required to do well in school, or have behavioural issues, the study noted.
May and his colleagues selected a nationally representative town in the Midwest for the study.
The town had an average annual alcohol consumption rate about 14 percent higher than the rest of the United States. That translated into roughly a litre of alcohol more per person per year, according to the study authors.
The town had 32 schools with a total of more than 2,000 first-graders. About 70 percent of the youngsters' parents allowed their children to participate in the study.
May's team identified first-graders who had a developmental problem or were below the 25th percentile for height, weight or head circumference. Then the researchers gave memory and thinking ("cognitive") tests, as well as behavioural tests, to these children and to a comparison group of typically developing first-graders.
The specially trained researchers also assessed the children for the physical attributes of foetal alcohol syndrome disorder, which include small eye openings, a smooth upper lip, a thin red border to the upper lip and smaller heads, May said.
The researchers found that six to nine of every 1,000 children had foetal alcohol syndrome. And, between 11 and 17 per 1,000 children had partial foetal alcohol syndrome, according to the study.
These numbers are higher than in previous research, but that may be due to the rigorous methods in the study, said Dr. Janet Williams, a professor of paediatrics at the University of Texas Health Science Centre in San Antonio.
"FASD is an umbrella term covering the full spectrum of permanent lifelong conditions, ranging from mild to severe, and encompassing a broad variety of physical defects and cognitive, behavioural, emotional and adaptive functioning deficits," Williams said.
"As we have better methodology, we're getting closer to the real prevalence, the real problem, and we need to stop the root cause of the problem."
This study also identified factors that predicted a higher risk that a child would have an FASD. The longer it took a mother to learn she was pregnant, how frequently she drank three months before pregnancy, and the more alcohol the child's father drank, the more likely it was that the child would have an FASD, the study found.
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There are multiple reasons rates of FASDs are high, said Dr. Lana Popova, a senior scientist at the Centre for Addiction and Mental Health and an assistant professor of epidemiology and of social work at the University of Toronto.
"First and foremost, women are receiving mixed messages about alcohol use during pregnancy through their family or friends, health care providers and public health campaigns," Popova said.
"Second, the rates of alcohol use, binge drinking and drinking during pregnancy appear to be increasing among young women in a number of countries."
A high number of unplanned pregnancies and a need to improve access to effective substance abuse treatment programs for women of childbearing age are two other contributing factors, Popova said.
"There is no safe amount of alcohol or safe time to drink during pregnancy, or when planning on becoming pregnant. If a woman is unaware of her pregnancy, for whatever reason, she should discontinue drinking immediately upon pregnancy recognition,"she said.
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Williams added that researchers continue to study the effects of even small amounts of alcohol during pregnancy because it is such a significant problem.
"Alcohol is a neurotoxin, and alcohol exposure is the leading preventable cause of birth defects and intellectual and neurodevelopmental disabilities," she said. "So why is it worth experimenting with your child?"
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Image: Pregnant woman drinking alcohol from Shutterstock.