New study published in Environmental Science & Technology finds prenatal exposure to chemical mixtures can affect fetal growth through placental function. Key findings include associations with birthweight and angiogenic biomarkers.

Prenatal exposure to complex chemical mixtures may influence fetal growth through the placenta, according to a recent study led by the Barcelona Institute for Global Health (ISGlobal) and published in Environmental Science & Technology. The research, conducted within the Barcelona Life Study Cohort (BiSC), highlights the importance of considering real-world exposures rather than single compounds.

Common environmental chemicals, such as phthalates, phenols, parabens, pesticides, and emerging compounds like bisphenol S (BPS), can enter the body through various means during pregnancy. Hormonal balance is crucial for placental development and fetal growth, with the placenta acting as a key endocrine organ that relies on tightly regulated angiogenic processes.

Bethany Knox, an ISGlobal researcher and first author of the study, explains, "Pregnant women are exposed to complex mixtures of chemicals rather than single compounds. Our goal was to better reflect real-world exposures and understand how these mixtures might influence both the placenta and fetal development."

The study involved 734 participants from the BiSC cohort in Barcelona, recruited between 2018 and 2021. Researchers analyzed exposure to more than 40 chemicals by measuring metabolites in pooled week-long urine samples collected at two stages of pregnancy: 18 and 34 weeks of gestation. This approach improves exposure assessment for non-persistent chemicals.

The research team identified distinct patterns in the associations of multiple chemical mixtures with fetal development. Exposure to mixtures of low molecular weight phthalates was consistently linked to lower birthweight, suggesting a potential adverse effect on fetal growth. In contrast, mixtures containing organophosphate compounds were associated with higher estimated fetal weight and birthweight, particularly in late pregnancy.

Knox notes, "This association may reflect dietary patterns rather than a direct effect of organophosphate exposure. Higher fruit and vegetable intake can increase exposure to these compounds while also supporting rapid fetal weight gain."

The study also points to the placenta as a key intermediary. Phthalate mixtures were associated with changes in fetoplacental blood flow and an imbalance in angiogenic biomarkers (sFlt-1/PlGF ratio), suggesting a biological pathway through which environmental exposures may influence fetal development.

Martine Vrijheid, Head of the Environment and Health over the Lifecourse Programme and coordinator of the study, emphasizes, "Our findings contribute to environmental health research by incorporating a broad panel of chemicals aligned with European regulatory priorities. While this study did observe deviations from normal fetal growth, they cannot be translated to an individual."

The study highlights the importance of considering environmental chemical mixtures in public health research, suggesting that widespread exposures may influence fetal development through their effects on placental function at the population level.

Publication details: Bethany Knox et al., Prenatal Exposure to Mixtures of Nonpersistent Endocrine-Disrupting Chemicals and Angiogenic Biomarkers, Placental Function, and Fetal Growth, Environmental Science & Technology (2026). DOI: 10.1021/acs.est.5c13234

Key Medical Concepts: Phthalic Acids Placenta

Clinical Categories: Obstetrics & Gynecology Pregnancy Women's Health Endocrinology