Exploratory Assessment of Preconception Phthalate Exposure on Fertility and Offspring Health in Mice

Infertility affects 10-15% of couples worldwide and is increasingly attributed to environmental exposures, particularly endocrine-disrupting chemicals (EDCs) such as phthalates. While gestational exposures are well studied, little is known about how preconception exposures influence fertility and offspring health. Phthalate exposure altered estrous cyclicity, with dams spending more time in proestrus and less in metestrus but did not significantly impact implantation or litter size. At E14.5, exposed fetuses exhibited increased bodyweights, accompanied by an expansion of the placental junctional zone in males. Altered bodyweight persisted into adulthood, however adulthood offspring displayed a reduction in bodyweight. RNA-sequencing revealed widespread transcriptional reprogramming in female placentas (518 DEGs) affecting immune regulation, steroid metabolism, and extracellular matrix remodeling, while male placentas exhibited only 9 DEGs but showed structural alterations. In offspring livers, transcriptomic shifts were sex-specific: females displayed downregulation of metabolic and immune genes (e.g., Cyp7a1, Mthfr, H2-DMB1), while males showed upregulation of immune and signaling genes (e.g., Elf4, Adm2, Ly6a). Collectively, these findings demonstrate that preconception phthalate exposure induces subtle but biologically meaningful maternal endocrine disruption, alters placental structure and function, and reprograms offspring growth and liver transcriptomes in a sex-specific manner. This work identifies the preconception window as a critical period of vulnerability for EDC impacts on reproductive success and intergenerational health.