For every additional drink a day on average during those early months, 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, reported Haruna Sawada Feldman, PhD, MPH, of the University of California San Diego in La Jolla, and colleagues.
There were similar findings for each additional episode of binge drinking and each additional drink in the maximum number consumed per occasion, the authors noted in the study, which appeared online ahead of print in Alcoholism: Clinical and Experimental Research.
Although FAS was first identified in 1973, little is known about the specific dose and timing of exposure to alcohol that increases the risk for birth defects. To further clarify the issue, researchers undertook a prospective study involving 992 women.
Data for the study was obtained from women enrolled in the California Teratogen Information Service and Clinical Research Program from 1978 to 2005. After getting counseling, women who reported exposure to at least 1 of 70 different agents, including alcohol, were interviewed in greater detail.
Pregnant women who reported no exposure to these agents were also asked if they would like to participate in the study.
At the end of the pregnancy, various outcome data were obtained. Timing of exposures was evaluated at 0 to 6 weeks after conception, 6 to 12 weeks following conception and then in the second and third trimesters.
For all live births, mothers were asked to participate in a standardized, blinded dysmorphological assessment of the child. The assessors, who were blinded for mother’s status, looked for a standardized checklist of 132 malformations. Multiple gestations were excluded and, if the women had more than one pregnancy, only the first eligible birth was included in the analysis.
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. These outcomes did not exclusively occur in the higher-dose group, the researchers noted.