The transfer of ethyl glucuronide across the dually perfused human placenta

The international prevalence of prenatal alcohol use obtained via meconium biomarkers: A systematic literature review

Fetal alcohol exposure is a growing public health concern. However, ascertaining its true extent remains challenging as maternal self-reports may lack validity. Increasingly, interest has turned to more objective measures of prenatal alcohol use (PAU) of which one, meconium, is recognized as a valuable tool. This review assesses both the international prevalence of PAU obtained using meconium biomarkers in general maternity populations and, when feasible, the level of agreement between meconium biomarkers and self-reported PAU. A systematic literature search for studies reporting the prevalence of PAU, as determined by meconium biomarker testing, was conducted using multiple electronic databases from 1990 to 2023. Seventeen studies were identified for inclusion and evaluated for methodological quality. Using fatty acid ethyl esters (FAEEs) meconium biomarkers, PAU prevalence varied from 2.4% to 44%. Rates based on EtG (ethyl glucuronide) analysis ranged from 0% to 16.3%, and EtS (ethyl sulfate) analysis from 7.8% to 16.7%. Studies were of moderate quality with high heterogeneity. Prevalence rates based on self-report data ranged from 0% to 46.4%. When reported, none of the reviewed studies identified agreement between meconium-based and self-report-based PAU prevalence rates. Using both self-reports to detect early pregnancy alcohol use, and meconium biomarkers to detect the occurrence of alcohol use later in pregnancy, may provide a more complete picture of PAU prevalence. Furthermore, research is warranted to develop stringent guidance on the ascertainment, storage, analysis, and reporting required in this field.

Assessing maternal alcohol consumption in pregnancy: comparison of confidential postnatal maternal interview and measurement of alcohol biomarkers in meconium

OBJECTIVE

Knowledge of alcohol consumption in pregnancy is important for early identification of children with fetal alcohol spectrum disorder. We investigated whether alcohol biomarkers fatty acid ethyl esters (FAEEs) and ethyl glucuronide (EtG) in meconium are predicted by maternal or newborn demographics and/or correlate with confidential early postnatal self-report of alcohol consumption in pregnancy.

DESIGN

Anonymised, observational population-based study.

SETTING

Inner-city maternity unit, Glasgow, UK.

PATIENTS

Singleton mother/infant dyads delivering every fourth day.

INTERVENTIONS

Mother: confidential postnatal interview. Baby: meconium sample for FAEEs and EtG.

RESULTS

840/908 mothers consented. 370 (46.4%) reported alcohol consumption in pregnancy, generally of modest amount; for 114 (13.6%) this was after 20 weeks' gestation. Alcohol consumption in later pregnancy was more commonly reported by older (31.3 vs 29.5 years) women of white British ethnicity (p<0.05); their babies were on average 118 g heavier (p=0.032). FAEEs were identified in all meconium samples; concentration was ≥600 ng/g in 39.6%. EtG concentration was ≥30 ng/g in 14.5%. Neither biomarker was associated with maternal age, body mass index or socioeconomic status but when EtG was ≥30 ng/g, the mother was less likely to identify as white British (71.3% vs 81.8%, p=0.028). Sensitivities of FAEEs ≥600 ng/g and EtG ≥30 ng/g were 43.1% and 11.6%, respectively for postnatal self-report of alcohol use in later pregnancy (specificities 60.6% and 84.8%).

CONCLUSIONS

FAEEs and EtG measured in meconium have low sensitivity and specificity for self-reported alcohol consumption after 20 weeks' gestation in an unselected Scottish population.

Quantifying fetal alcohol exposure by meconium fatty acid ethyl esters (FAEE); association with adverse fetal outcomes and population estimates of fetal alcohol exposure

Fetal Alcohol Spectrum Disorder (FASD) describes the wide range of adverse physical, behavioral and cognitive effects resulting from ethanol exposure during embryonic and fetal development. Identification of children suffering from FASD is often difficult, as abuse of ethanol during pregnancy is a heavily stigmatized behavior that receives little prenatal screening attention in routine care. Over the last 3 decades, measurement of the ethanol metabolites fatty acid ethyl esters (FAEE) has emerged as a useful tool to detect in the neonatal period fetal alcohol exposure starting from mid gestation. This review aims at updating clinicians and researchers on the validity and utility of this biological marker in two aspects: The association with adverse fetal outcomes and in generating population estimates of fetal alcohol exposure.

Placental control of drug delivery

The placenta serves as the interface between the maternal and fetal circulations and regulates the transfer of oxygen, nutrients, and waste products. When exogenous substances are present in the maternal bloodstream-whether from environmental contact, occupational exposure, medication, or drug abuse-the extent to which this exposure affects the fetus is determined by transport and biotransformation processes in the placental barrier. Advances in drug delivery strategies are expected to improve the treatment of maternal and fetal diseases encountered during pregnancy.

Biomarkers for the Detection of Prenatal Alcohol Exposure: A Review

Alcohol exposure during pregnancy can cause adverse effects to the fetus, because it interferes with fetal development, leading to later physical and mental impairment. The most common clinical tool to determine fetal alcohol exposure is maternal self-reporting. However, a more objective and useful method is based on the use of biomarkers in biological specimens alone or in combination with maternal self-reporting. This review reports on clinically relevant biomarkers for detection of prenatal alcohol exposure (PAE). A systematic search was performed to ensure a proper overview in existing literature. Studies were selected to give an overview on clinically relevant neonatal and maternal biomarkers. The direct biomarkers fatty acid ethyl esters (FAEEs), ethyl glucuronide (EtG), ethyl sulfate, and phosphatidylethanol (PEth) were found to be the most appropriate biomarkers in relation to detection of PAE. To review each biomarker in a clinical context, we have compared the advantages and disadvantages of each biomarker, in relation to its window of detectability, ease of collection, and the ease and cost of analysis of each biomarker. The biomarkers PEth, FAEEs, and EtG were found to be applicable for detection of even low levels of alcohol exposure. Meconium is an accessible matrix for determination of FAEEs and EtG, and blood an accessible matrix for determination of PEth.

Fetal alcohol-spectrum disorders: identifying at-risk mothers

Fetal alcohol-spectrum disorders (FASDs) are a collection of physical and neurobehavioral disabilities caused by prenatal exposure to alcohol. To prevent or mitigate the costly effects of FASD, we must identify mothers at risk for having a child with FASD, so that we may reach them with interventions. Identifying mothers at risk is beneficial at all time points, whether prior to pregnancy, during pregnancy, or following the birth of the child. In this review, three approaches to identifying mothers at risk are explored: using characteristics of the mother and her pregnancy, using laboratory biomarkers, and using self-report assessment of alcohol-consumption risk. At present, all approaches have serious limitations. Research is needed to improve the sensitivity and specificity of biomarkers and screening instruments, and to link them to outcomes as opposed to exposure. Universal self-report screening of all women of childbearing potential should ideally be incorporated into routine obstetric and gynecologic care, followed by brief interventions, including education and personalized feedback for all who consume alcohol, and referral to treatment as indicated. Effective biomarkers or combinations of biomarkers may be used during pregnancy and at birth to determine maternal and fetal alcohol exposure. The combination of self-report and biomarker screening may help identify a greater proportion of women at risk for having a child with FASD, allowing them to access information and treatment, and empowering them to make decisions that benefit their children.

A novel, simultaneous extraction of FAEE and EtG from meconium and analysis by LC-MS/MS

Fatty acid ethyl esters (FAEEs) and ethyl-glucuronide (EtG) in meconium have been widely studied as biomarkers of maternal alcohol consumption during pregnancy. Many analytical approaches have been proposed for their analysis, mostly consisting of separated extraction procedures requiring the use of two meconium aliquots. This study aimed to validate a new analytical procedure for the simultaneous extraction of FAEEs and EtG from a meconium aliquot through a single solid-phase extraction (SPE) applied to 242 anonymized samples of meconium. Targeted FAEEs were: ethyl-myristate (Myr), ethyl-palmitate (Pal), ethyl-oleate (Ole) and ethyl-stearate (Ste). Two hundred milligrams of meconium was sonicated with acetonitrile, and a single SPE performed by means of aminopropyl columns. FAEEs were eluted with hexane, followed by EtG elution with water. Both the mixtures were dried, recovered, and analyzed by liquid chromatography-tandem mass spectrometry using C8 (FAEEs) and C18 (EtG) columns. Transitions were: m/z 257 → 57,88, Myr; m/z 262 → 57,88, Myr-d5; m/z 285 → 57, 72, Pal; m/z 290 → 57,258, Pal-d5; m/z 311 → 72,114, Ole; m/z 316 → 72,265, Ole-d5; m/z 257 → 57,72 Ste; m/z 318 → 57,286, Ste-d5; m/z 221 → 75,85, EtG; m/z 226 → 75,85, EtG-d5. Lower limit of quantification range was 10-15 ng/g for FAEEs and 10 ng/g for EtG. Linearity was evaluated for different concentration ranges; the mean coefficients of determination (R (2)) were above 0.9961. Precision and accuracy for FAEEs and EtG were consistently ≤20 % and ±20 %, respectively. Ion suppression was observed for all the analytes. Matrix effect did not significantly affect the analyses. Recovery efficiency was 93 % for EtG and 75-85 % for FAEEs.

Rivaroxaban transfer across the dually perfused isolated human placental cotyledon

OBJECTIVE

The purpose of this study was to determine the rate and extent of rivaroxaban transfer across the term human placenta and determine whether passive diffusion was the primary mechanism involved in this transfer.

STUDY DESIGN

The transplacental pharmacokinetics of rivaroxaban was determined with the ex-vivo placenta perfusion model. Rivaroxaban was added to the maternal or fetal circulation only (250 ng/mL). Additional experiments were conducted under equilibrative conditions with the addition of rivaroxaban to both the maternal and fetal circulations (250 ng/mL). Rivaroxaban concentrations were measured with the use of liquid chromatography-tandem mass spectrometry.

RESULTS

There was rapid transfer of rivaroxaban across the human placenta in both the maternal-to-fetal and fetal-to-maternal directions, as evidenced by transfer ratios of 0.69 (interquartile range, 0.58-0.73; n = 5) and 0.69 (interquartile range, 0.67-0.71; n = 2), respectively, after 3 hours. Under equilibrative conditions (n = 2), rivaroxaban concentrations remained relatively constant, which suggests that rivaroxaban crosses the placenta down a concentration gradient.

CONCLUSION

This is the first direct evidence of rivaroxaban transfer across the term human placenta from both the mother-to-fetus and fetus-to-mother directions. Our results document that unbound rivaroxaban rapidly crosses the placental barrier via passive diffusion. However, because rivaroxaban is highly bound to plasma proteins (up to 95%), this suggests that the amount of unbound drug that may reach the fetus is likely much lower. Additional studies will need to explore its safety before administering rivaroxaban to a pregnant woman.

Antiretroviral Drugs in Meconium: Detection for Different Gestational Periods of Exposure

OBJECTIVES

To determine whether antiretroviral (ARV) medications can be detected in meconium from second or third trimester, labor and delivery (L&D), or postnatal exposures.

STUDY DESIGN

Twenty ARV medications were quantified by liquid chromatography-tandem mass spectrometry in 598 meconium samples from uninfected infants born to pregnant women with HIV enrolled in the Pediatric HIV/AIDS Cohort Study.

RESULTS

ARV detection in meconium following third trimester exposure was 85.7%-94.4% for all ARVs except stavudine (0%, n = 2), likely because of low doses and a high limit for quantification. Of 107 samples with some second trimester only ARV exposures, meconium was positive for only lopinavir, tenofovir, or efavirenz in 11.8%-14.3% of exposed neonates; administration of these ARVs occurred between gestational weeks 25-28 in the positive samples. Days without lopinavir or tenofovir before delivery significantly correlated with decreasing concentrations of lopinavir and tenofovir in meconium. Tenofovir and lamivudine concentrations significantly correlated with increasing gestational age among infants with continuous second and third trimester exposure. Zidovudine given during L&D or for neonatal prophylaxis was detected in 95.1% and 94.6% of meconium samples, respectively.

CONCLUSIONS

Changes in ARV treatments during pregnancy offered a unique opportunity to investigate ARV detection in meconium. ARVs in meconium primarily reflect third trimester ARV exposures, although 6 of 107 second trimester only exposures were detected. Zidovudine administration during L&D was detected in meconium indicating potential urine contamination or rapid incorporation into meconium. These data will improve interpretation of meconium drug test results.

Clinical sensitivity and specificity of meconium fatty acid ethyl ester, ethyl glucuronide, and ethyl sulfate for detecting maternal drinking during pregnancy

BACKGROUND

We investigated agreement between self-reported prenatal alcohol exposure (PAE) and objective meconium alcohol markers to determine the optimal meconium marker and threshold for identifying PAE.

METHODS

Meconium fatty acid ethyl esters (FAEE), ethyl glucuronide (EtG), and ethyl sulfate (EtS) were quantified by LC-MS/MS in 0.1 g meconium from infants of Safe Passage Study participants. Detailed PAE information was collected from women with a validated timeline follow-back interview. Because meconium formation begins during weeks 12-20, maternal self-reported drinking at or beyond 19 weeks was our exposure variable.

RESULTS

Of 107 women, 33 reported no alcohol consumption in pregnancy, 16 stopped drinking by week 19, and 58 drank beyond 19 weeks (including 45 third-trimester drinkers). There was moderate to substantial agreement between self-reported PAE at ≥19 weeks and meconium EtG ≥30 ng/g (κ = 0.57, 95% CI 0.41-0.73). This biomarker and associated cutoff was superior to a 7 FAEE sum ≥2 nmol/g and all other individual and combination marker cutoffs. With meconium EtG ≥30 ng/g as the gold standard condition and maternal self-report at ≥19 weeks' gestation as the test condition, 82% clinical sensitivity (95% CI 71.6-92.0) and 75% specificity (95% CI 63.2-86.8) were observed. A significant dose-concentration relationship between self-reported drinks per drinking day and meconium EtG ≥30 ng/g also was observed (all P < 0.01).

CONCLUSIONS

Maternal alcohol consumption at ≥19 weeks was better represented by meconium EtG ≥30 ng/g than currently used FAEE cutoffs.

Incidence of prenatal alcohol exposure in Prince Edward Island: a population-based descriptive study

BACKGROUND

Fetal alcohol spectrum disorder (FASD) is a leading preventable cause of neurodevelopmental disability in North America. The stigma associated with alcohol use and abuse during pregnancy makes it difficult to obtain information on prenatal alcohol use through self-reporting. We assessed the incidence of prenatal alcohol exposure in Prince Edward Island to facilitate future public health initiatives addressing FASD.

METHODS

Prenatal alcohol exposure was examined via population-based collection of meconium and analysis of fatty acid ethyl esters (FAEEs). Fatty acid ethyl esters are nonoxidative metabolites of ethanol that are produced in the fetus. Meconium FAEE concentrations of 2.0 nmol/g or greater are indicative of frequent prenatal alcohol exposure during the last 2 trimesters of pregnancy. Samples were collected from 1307 neonates between Nov. 8, 2010, and Nov. 8, 2011, in hospitals in PEI, or from those born to mothers who resided in PEI but gave birth in Halifax, Nova Scotia. Samples were frozen and shipped for analysis. Fatty acid ethyl esters were analyzed by gas chromatography-mass spectrometry and quantified by means of deuterated internal standards.

RESULTS

Of the 1307 samples collected, 1271 samples were successfully analyzed. Positive results for FAEEs were obtained in 3.1% (n = 39) of samples collected within the first 24 hours after birth.

INTERPRETATION

Not all neonates exposed to heavy prenatal alcohol in utero will exhibit FASD; based on current estimates of predictive value for disease by exposure, our findings suggest that 1.3% of neonates born in PEI during this 1-year period will have FASD. In its application to an entire provincial birth cohort, this study successfully implemented a public health-centred approach for evaluating population-based risk of FASD, with implications for practice across Canada.

Validation of a novel method to identify in utero ethanol exposure: simultaneous meconium extraction of fatty acid ethyl esters, ethyl glucuronide, and ethyl sulfate followed by LC-MS/MS quantification

Presence of fatty acid ethyl esters (FAEE), ethyl glucuronide (EtG), and ethyl sulfate (EtS) in meconium, the first neonatal feces, identifies maternal alcohol consumption during pregnancy. Current meconium alcohol marker assays require separate analyses for FAEE and EtG/EtS. We describe development and validation of the first quantitative liquid chromatography tandem mass spectrometry assay for 9 FAEEs, EtG, and EtS in 100 mg meconium. For the first time, these alcohol markers are analyzed in the same meconium aliquot, enabling comparison of the efficiency of gestational ethanol exposure detection. 100 mg meconium was homogenized in methanol and centrifuged. The supernatant was divided, and applied to two different solid phase extraction columns for optimized analyte recovery. Limits of quantification for ethyl laurate, myristate, linolenate, palmitoleate, arachidonate, linoleate, palmitate, oleate, and stearate ranged from 25-50 ng/g, with calibration curves to 2,500-5,000 ng/g. EtG and EtS linear dynamic ranges were 5-1,000 and 2.5-500 ng/g, respectively. Mean bias and between-day imprecision were <15 %. Extraction efficiencies were 51.2-96.5 %. Matrix effects ranged from -84.7 to 16.0 %, but were compensated for by matched deuterated internal standards when available. All analytes were stable (within ±20 % change from baseline) in 3 authentic positive specimens, analyzed in triplicate, after 3 freeze/thaw cycles (-20 °C). Authentic EtG and EtS also were stable after 12 h at room temperature and 72 h at 4 °C; some FAEE showed instability under these conditions, although there was large inter-subject variability. This novel method accurately detects multiple alcohol meconium markers and enables comparison of markers for maternal alcohol consumption.