Exploring stress and hormonal markers during pregnancy through nail analysis

Monitoring stress and hormonal changes during pregnancy is essential for understanding maternal and fetal health, but traditional sampling methods can be invasive and limited in scope. A recent study from the University of Zurich explores fingernail analysis as a non-invasive alternative for biomarker tracking. Because nails are a solid, keratinized matrix, effective sample preparation is a critical step to ensure accurate analysis.

Why nails? A stable, non-invasive matrix

The use of nails as a biological matrix is gaining increasing attention in clinical research due to their easy, non-invasive collection and medium to long term monitoring capabilities.

Unlike other biological matrices like blood or saliva, nail clippings require minimal storage and are easy to transport. The matrix is relatively stable, and does not require temperature control, removing the need for refrigerated storage containers and reducing costs.

Adult fingernails grow at an average rate of approximately 3mm per month, making them a suitable matrix for estimating timelines of exposure or ingestion of exogenous compounds, such as drugs of abuse.

Using nails to provide a representation of drug use over a specific period can be used to continually monitor a donor in cases such as family law, where a parent may need to prove abstinence from drugs for a particular period.

Beyond drugs of abuse, endogenous biomarker concentrations can also be quantified in nails, providing insight into physiological compound levels over specific time periods, for example, hormone levels during periods of stress. Fingernails begin to develop around 7-8 weeks in the uterus, with a completely differentiated nail matrix developed by 20 weeks gestation. This makes nails an effective matrix for detecting compounds to which a baby has been exposed to during development.

The biomarkers: Endocannabinoids and steroid hormones

The endocannabinoid system plays a central role in regulating key physiological functions such as cognition, stress response, sleep, mood, and appetite. It is composed of cannabinoid receptors, endogenous cannabinoids (endocannabinoids), and the enzymes responsible for their synthesis and degradation. Endocannabinoids are naturally produced lipids that bind to cannabinoid receptors in response to various stimuli, thereby influencing a range of bodily processes. During pregnancy, they are involved in critical events such as embryo implantation, placental development, and immune modulation.

Steroid hormones are also endogenous compounds that are derived from cholesterol and are secreted by the adrenal cortex, testes and ovaries, and during pregnancy, also by the placenta. They are transported through the bloodstream to target organs to carry out regulation of a range of physiological functions, including metabolism, immune response, and fetal development.

Understanding stress and hormonal regulation during pregnancy

Adverse outcomes, such as increased rate of preterm birth, have been linked to stress exposure during pregnancy, with both steroid hormones and endocannabinoids playing important roles in fetal development. Sample collection techniques for blood, saliva or urine provide hormone levels for only a limited period, and collection of samples from fetal fluids is challenging and invasive.

Therefore, Clarissa Voegel et al carried out a feasibility study to further understand the incorporation of steroid hormones and endocannabinoids in fingernails of pregnant women and their infants. The aims of the study were to identify optimal sampling time points for future studies into perinatal stress research and evaluate fingernail analysis as a non-invasive sampling technique.

The research team tracked five mothers and four infants across multiple time points during pregnancy and up to four months postpartum, collecting a total of 67 maternal nail samples. They analyzed four endocannabinoids (2-arachidonylglycerol (2-AG), anandamide (AEA), oleoylethanolamide (OEA), palmitoylethanolamide (PEA)) and five steroid hormones (cortisone, cortisol, androstenedione, testosterone, progesterone) from the fingernails collected from mothers and their infants. The compounds were quantified at different time points pre- and post-birth to reveal concentrations during pregnancy.

Methodology: Efficient extraction of keratinized matrices

Due to the solid and keratinized nature of the nail matrix, thorough sample preparation is essential prior to analysis. Following an initial washing step, nail samples were pulverized and homogenized, which can be performed using a bead mill homogenizer such as the Biotage® Lysera, enabling efficient and reproducible extraction of analytes from the solid matrix. This was followed by sonication and clean-up using ISOLUTE® SLE+, an easy to use, simple load-wait-elute procedure ideal for aqueous samples, including a range of biological fluids. Automation of this method was performed on a Biotage® Extrahera™ Classic providing streamlined sample preparation by process multiple samples simultaneously and improved reproducibility prior to LC-MS/MS analysis for accurate quantification of low-level analytes.

What the study revealed

The investigation carried out by Clarissa Voegel et al. demonstrated that the use of fingernails as a matrix can effectively track endogenous biomarkers during and after pregnancy. Based on their findings, the team recommends three optimal sampling periods for future studies:

• - At 20-32 weeks gestation
• - Up to 4 weeks postpartum
• - Between 2-4 months postpartum
•  

These time points capture the most significant hormonal changes while minimizing participant burden. The study opens several areas for future investigation, including exploring relationships between fingernail biomarker levels and specific pregnancy outcomes such as pre-term delivery.

Access the full article on ScienceDirect:

Voegel, C., et al. (2025). Endocannabinoid and steroid hormone levels during and after pregnancy in fingernail samples from mothers and their infants. Steroids, October 2025, 109663

Related content/products/resources:

Biotage® Lysera

ISOLUTE® SLE+

Biotage® Extrahera™ Classic

App note: Streamlined Sample Preparation of a Drugs of Abuse Panel in Human Nails Using ISOLUTE® SLE+ Prior to UPLC-MS/MS Analysis