No safe threshold for prenatal alcohol exposure

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No Safe Threshold Found for Prenatal Alcohol Exposure
No Safe Threshold Found for Prenatal Alcohol Exposure

HealthDay News --  Any alcohol consumption during pregnancy may put an infant at risk for fetal alcohol syndrome (FAS), with no evidence of a safe threshold, according to study data published in Alcoholism: Clinical & Experimental Research.

"Women should continue to be advised to abstain from alcohol consumption from conception throughout pregnancy," Haruna Sawada Feldman, PhD, MPH, from the University of California in San Diego, and colleagues wrote.

Although FAS was first identified in 1973, the relationship between specific dose and timing of alcohol exposure and risk for developing FAS birth defects has been poorly understood. So Feldman and colleagues examined data from 992 women enrolled in the California Teratogen Information Service and Clinical Research Program from 1978 to 2005, in an effort to determine how these factors influence risk. Timing of exposure to alcohol was evaluated at 0 to 6 weeks after conception, 6 to 12 weeks following conception and then in the second and third trimesters. Blinded dysmorphological assessment was performed for a standardized checklist of 132 malformations.

The researchers found that prenatal alcohol exposure correlated with incidence of the physical features of FAS,  with the strongest association observed between smooth philtrum incidence and exposure during the second half of the first trimester (relative risk [RR] for average number of drinks per day=1.25; 95% CI:1.14-1.36; RR for maximum number of drinks in one episode=1.17; 95% CI: 1.09-1.26).

During the second trimester, significant associations were seen with smooth philtrum, and weight and length. By the last trimester, only birth length was associated with average drinks per day and maximum number at one occasion.

When women consuming one or more drinks per day were compared to those consuming less during the first trimester, higher risk was seen with higher dose for microcephaly, thin vermillion border and smooth philtrum, as well as reduced birth length and weight. However, these outcomes did not exclusively occur in the higher-dose group, the researchers noted.

"There was no indication of a threshold amount of alcohol exposure that is safe with respect to the specific outcomes that demonstrated a significant association with exposure," the researchers wrote.

Instead the associations were linear, with incrementally higher prenatal alcohol exposure associated with incremental increased risk. For every additional drink a day on average during the second half of the first trimester, there were increased risks of 25% for smooth philtrum, 22% for thin vermilion, 12% for microcephaly, 16% for lower birth weight, and 18% for reduced birth length, the researchers found.

Study limitations included a volunteer-based participants that may not be representative of the entire population and reliance on maternal reports of alcohol consumption, which may have resulted in under- or misreporting.

"It is thought that far more children with prenatal exposure to alcohol are affected neurobehaviorally than those who exhibit structural features of FAS," the researchers wrote. "Future studies should address these same questions regarding gestational timing and dose relative to neurobehavioral outcomes."

Feldmen HS et al. Alcohol Clin Exp Res. 2012; doi:10.111/j.1530-0277.2011.01664.x.


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