Phosphatidylethanol is a promising tool for screening alcohol consumption during pregnancy

Prenatal alcohol exposure (PAE) is one of the leading causes of preventable developmental disabilities. A lack of objective screening methods results in an under-recognition of the phenomenon. Phosphatidylethanol (PEth) is a specific ethanol biomarker that reveals alcohol intake up to several weeks after alcohol use. So far, PEth has mostly been a tool for detecting moderate and heavy drinking. With lower PEth cut-offs, revealing even minor prenatal alcohol consumption is possible. We aimed to find out if a sensitive method for PEth analysis would give additional information about PAE and to assess the cut-off value for a positive alcohol result in prenatal screening.

The study was an observational study of 3000 anonymous blood samples collected from the Helsinki University Hospital Diagnostic Center between June and September 2023. The Finnish Red Cross Blood Service received the samples originally for blood group typing and antibody screening as part of the prenatal blood screening program. We developed a sensitive PEth 16:0/18:1 analysis method using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) equipment after liquid-liquid extraction of PEth from whole blood. The lower limit of quantification was 1 ng/mL.

PEth was ≥2 ng/mL in 5.2% of the cases, ≥8 ng/mL in 2.0%, and ≥20 ng/mL in 1.0%. The detection time of PEth can be several weeks, especially with low PEth concentrations and after heavy alcohol consumption. It remained unknown whether the positive PEth tests resulted from drinking deliberately during pregnancy or before pregnancy recognition.

We suggest adding PEth 16:0/18:1 to a routine prenatal blood screening program with a cut-off of 2 ng/mL-and in positive cases, clinical evaluation and retesting in 2-4 weeks. In clinical settings, information on gestational week and alcohol consumption before pregnancy is relevant and needs to be considered when interpreting low PEth concentrations.