Nanoparticle Delivery of Fetal Therapies.

Advances in high-resolution fetal imaging and molecular diagnostics have significantly improved the prenatal detection of congenital conditions. However, commensurate therapeutic options remain limited. While existing fetal surgical and pharmacological interventions can be effective, they fail to address fundamental therapeutic delivery problems, and are limited by low drug solubility, rapid circulatory dilution, and systemic clearance. Nanoparticle (NP) delivery systems offer a compelling solution to these barriers. By modifying how therapeutics behave post-administration, NPs enable effective delivery of a wide variety of cargos across maternal and fetal administration routes. Depending on the specific formulation and chosen route of administration, NPs can protect labile cargo, alter biodistribution, support controlled release, and improve cellular uptake. This review outlines NP-based approaches for fetal therapy, detailing potential administration routes based on the target biological compartment. We systematically examine the major classes of relevant nanocarrier platforms (lipid-based, polymer-based, inorganic and carbon-based), highlighting how their distinct structural and chemical features impact on payload compatibility. Finally, we discuss the regulatory framework governing intentional fetal exposure to nanoparticles, highlighting the critical need for indication-specific biodistribution profiling and developmental toxicity studies to successfully translate nanomedicines into the clinic.