Exposure to certain synthetic chemicals during pregnancy may alter early childhood behaviour, according to a new study from European researchers. The investigation focused on synthetic phenols, which are widely used in plastics, cosmetics, and household products. These chemicals have been suspected of interfering with hormone systems, potentially affecting brain development before birth.
The research team combined data from two large European birth cohorts: the Barcelona Life Study Cohort (BiSC) in Spain and the SEPAGES study in France. Together, they followed 1,024 mother–child pairs, analysing repeated urine samples from pregnancy for 12 synthetic phenols. Child behaviour was assessed between 18 and 24 months of age using the Child Behavior Checklist, a standard tool for identifying early emotional and behavioural problems.
Key Findings
Mothers with higher methylparaben exposure during the third trimester had children who scored higher on internalising and externalising scales, suggesting more symptoms such as anxiety, withdrawal, or aggression. Among boys, exposure to bisphenol S was associated with higher internalising scores and a possible increase in externalising behaviours.
In contrast, girls whose mothers had greater exposure to butylparaben and propylparaben during the second trimester showed lower scores on both internalising and externalising measures. The findings suggest that prenatal chemical exposure may influence behavioural development in a sex-specific way, with boys and girls responding differently.
Hormonal Pathways and Policy Implications
The team measured maternal hair samples to explore whether steroid hormones might mediate these effects, but no significant evidence supported this link. The absence of mediation suggests that synthetic phenols may act through other biological mechanisms.
Researchers emphasize that these results, together with previous evidence, point to a growing need for stricter controls on synthetic phenols. Even small shifts in behaviour at this early stage could have long-lasting impacts on development. The authors call for stronger regulations to limit exposure during pregnancy and for further studies to uncover how these common chemicals affect the developing brain.
Reference
Rolland M et al. Prenatal phenol exposure and child behaviour: insights into the hypothalamic–pituitary–adrenal axis from two prospective mother–child cohorts. The Lancet Planetary Health. 2025;101330.
