Both the intervention and control subjects had a postpartum follow-up interview to review the frequency and quantity of alcohol consumed during pregnancy as well as changes in alcohol-related health habits since enrollment. “We had a 95% follow-up rate overall, and only 3% of partners were ultimately unable to participate in one part of the study or another,” Dr. Chang noted.
The investigators used univariate and multivariate analyses to compare the intervention and control groups before and after study enrollment, and least squares regression models were used to evaluate the effect of the intervention on three dependent variables: alcohol consumption quantity, frequency, and both.
When the two groups were compared, “there were no statistically significant differences in the amount or frequency of prepregnancy alcohol consumption, and most of the women in both conditions demonstrated overall reduced alcohol consumption once enrolled,” Dr. Chang said. “Many of the women spontaneously decreased the frequency of their alcohol consumption to a mean of 5% drinking days, although fewer than 20% were abstinent.”
The results of an intention-to-treat analysis showed a significant interaction between the intervention and prenatal alcohol consumption, Dr. Chang reported. “The brief intervention was most effective in reducing the frequency of consumption among women who drank more at the time of the study enrollment,” she said. Additionally, “the intervention was more effective for heavier drinking subjects when the partner was involved.”
The analyses identified additional variables that increased the risk of prenatal alcohol consumption: prenatal alcohol use before the study, level of education, temptation to drink in social situations, and number of years of regular alcohol use.