Nicotine and its metabolites in amniotic fluid at birth--assessment of prenatal tobacco smoke exposure.

Amniotic fluid was collected from 78 pregnant women at birth additionally with their urine prior to delivery as well as neonatal urine and meconium. The smoking markers, nicotine and its metabolites cotinine and trans-3'-hydroxycotinine (OH-cotinine), were determined using high-performance liquid chromatography (HPLC). The self-reported smoking status during pregnancy determined by means of a questionnaire was verified by measurement of maternal urine. In all smokers, nicotine metabolites were detected in amniotic fluid and in 80% of them nicotine as well. However, the sum of the nicotine metabolites (Sum(met)) was significantly lower (p < .001) in amniotic fluid (704 +/- 464 nmol/L) than in meconium (921 +/- 588 nmol/L), neonatal urine (1139 +/- 813 nmol/L) and maternal urine (4496 +/- 3535 nmol/L). Concentrations of nicotine metabolites in amniotic fluid correlated well (p < .001) with that in the other specimen types. After environmental tobacco smoke (ETS) exposure, no nicotine or nicotine metabolites were detectable in amniotic fluid but only in maternal and neonatal urine. Analysis of amniotic fluid at birth lends itself to verifying smoking habits during pregnancy and clearly discriminating from ETS exposure, but it is not a suitable approach to differentiating between ETS exposure and non-exposure.