Identifying high-risk subgroups for alcohol consumption among younger and older pregnant women

Recent studies indicate that older women are more likely to consume alcohol during pregnancy, but subgroups at highest risk within the context of maternal age have not been identified. This study identifies subgroups at risk for alcohol use during pregnancy among three age categories using classification and regression trees (CART) analysis.

Using the 2002-2009 Pregnancy Risk Assessment Monitoring System (PRAMS) dataset (311,428 records of U.S. women), logistic regression and classification trees were constructed separately for age groups, ≤24, 25-29, and ≥30 years.

Overall, 6.5% of women reported drinking alcohol during the last trimester of pregnancy. Alcohol consumption by age group was: 3.7% for ≤24, 5.7% for 25-29, and 10.1% for ≥30 years of age. Women ≤24 years were at greater risk of consuming alcohol if they also smoked (5.8%). Among nonsmokers, higher levels of education and being Hispanic were associated with a 35% increase in alcohol use. Distinct high-risk subgroups emerged for the 25-29-year-old group. Specifically, 12.8% of non-obese women who reported having experienced abuse during pregnancy also reported drinking alcohol in the last trimester. About 16% of women ≥30 years with at least 16 years of education, White or Hispanic with normal or underweight BMI, drank alcohol during their last trimester.

Given limited health care resources for prevention and treatment, the early identification of high-risk groups for prenatal alcohol use is critical. This study provides evidence that risk factors contributing to alcohol consumption during pregnancy may differ by maternal age.