Biological matrices for the evaluation of in utero exposure to drugs of abuse

In recent years, the evaluation of in utero exposure to drugs of abuse has been achieved by testing biological matrices coming from the fetus or newborn (eg, meconium, fetal hair, cord blood, neonatal urine), the pregnant or nursing mother (eg, hair, blood, oral fluid, sweat, urine, breast milk), or from both the fetus and the mother (placenta, amniotic fluid). Overall, these matrices have the advantage of noninvasive collection (with the exception of amniotic fluid) and early detection of exposure from different gestational periods. Matrices such as amniotic fluid, meconium, fetal hair, and maternal hair provide a long historical record of prenatal exposure to certain drugs and can account for different periods of gestation: amniotic fluid from the early pregnancy, meconium for the second and third trimester of gestation, fetal hair for the third, and finally maternal hair (when long enough) for the whole pregnancy. Placenta may reveal the passage of a substance from the mother to the fetus. Cord blood and neonatal urine are useful for determining acute exposure to drugs of abuse in the period immediately previous to delivery. Drug detection in maternal blood, oral fluid, and sweat accounts only for acute consumption that occurred in the hours previous to collection and gives poor information concerning fetal exposure. Different immunoassays were used as screening methods for drug testing in the above-reported matrices or as unique analytical investigation tools when chromatographic techniques coupled to mass spectrometry were not commonly available. However, in the last decade, both liquid and gas chromatography-mass spectrometric methodologies have been routinely applied after appropriate extraction of drugs and their metabolites from these biological matrices.