Prevalence of prenatal exposure to substances of abuse: questionnaire versus biomarkers

Alcohol and drugs of abuse consumption in young adults, including women of childbearing age, has experienced significant increase over the past two decades. The use of questionnaires as the only measure to investigate prenatal alcohol and drugs of abuse exposure underestimates the real prevalence of exposure and could mislead to wrong conclusions. Therefore, the aim of this article was to compare reported rates of prenatal alcohol and drugs of abuse consumption with biomarkers of exposure by a comprehensive review of the available literature. We searched MEDLINE and EMBASE databases for articles catalogued between 1992 and 2015. We identified relevant published studies that assessed the comparison between prenatal exposure to alcohol and drugs of abuse assessed by self-reported questionnaire of consumption versus biomarkers of exposure. Thirteen studies were included regarding alcohol consumption, and seven of them about drugs of abuse. Women who admitted consumption during pregnancy by questionnaire varied from 0 to 37% for alcohol, from 0 to 4.3% for cocaine, and 2.9% for tetrahydrocannabinol (THC). Positive biomarkers results ranged from 16 to 44% for alcohol, 15.4% for cocaine, and from 4 to 12.4% for THC. Biomarkers should always complement questionnaires, as it has been shown that self-report may underestimate prenatal exposure to substances of abuse.