The intervention and control subjects underwent a postpartum follow-up interview to review the frequency and quantity of alcohol consumed during pregnancy and changes in alcohol-related health habits since the time of 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 said. “The brief intervention was most effective in reducing the frequency of consumption among women who drank more at the time of the study enrollment. The intervention was more effective for heavier drinking subjects when the partner was involved. It was really quite exciting to see that, because most of the previous research regarding partner influence has focused on two areas: prenatal cigarette smoking, where the partner's smoking habits are strong predictors of the woman's; and breast-feeding, where partner support is an important factor.”
The analyses also identified several additional variables that increased the risk of prenatal alcohol consumption: the amount of prenatal alcohol use before study enrollment, level of education, temptation to drink in social situations, and number of years of regular alcohol use. “We found that the strongest predictor was alcohol use at the previous time—lifetime use predicted prepregnancy use, prepregnancy use predicted early pregnancy use, and so on,” Dr. Chang said. “Partners' drinking was not a predictor, which was a surprise; nor was knowledge of risks a predictor.”