Drugs prescribed to pregnant women are frequently used “off label” because trials of new drugs in pregnancy are seldom performed. In order to improve pregnancy outcomes with more effective and safer therapeutics, methods of delivering drugs are needed that allow the selective targeting of maternal, placental or fetal tissues while avoiding unwanted off-target effects. Currently, most drugs given maternally reach all major organs via the maternal circulation, including the placenta. The placental barrier varies according to gestational age and the structure of the drug in question.

Drug delivery via nanoparticles offers enormous advantages over existing drug delivery strategies. Nano-sized drug carriers (typically 5-500 nm diameter) can be optimised in terms of their chemical composition, size, uptake properties, plasma half-life/clearance and immunogenicity. They can be tailored to deliver drugs that may be ineffective when given via conventional routes. They can be used to reduce the dose of a drug by ensuring its efficient delivery. Most excitingly, nanoparticles can be functionalised to target specific cell types or tissues and thus restrict their actions to those tissues that would benefit from the therapy.

Nanoparticle-mediated drug delivery has enormous potential for the treatment of pregnancy disorders. The placenta, with unfettered access to substances circulating in the maternal blood stream, offers an excellent therapeutic target as well as a potential conduit for fetal drug administration. Studies suggest that the uptake and passage of nanomaterials across the placenta can be controlled by altering their size, structure and charge. Targeting strategies are opening the door for the development of therapeutics that could be given maternally to improve placental function, selectively address a maternal disorder, or correct a fetal genetic defect without affecting maternal organs or systems.

Already, nanoparticle drug preparations for the treatment of a variety of conditions and are on the market, and their numbers are predicted to grow rapidly over the next decade. The next few years should see this technology being exploited in preclinical and clinical trials in pregnancy.