Objectives A major challenge in drug therapy is to develop safe and selective targeting strategies during pregnancy and lactation. Use of any drug during pregnancy is complicated by concerns of adverse effects on the pregnant woman and the fetus. Drugs administered orally or parenterally to the mother reach the systemic circulation and have a potential to pass to the fetus. The importance of the drugs transported from the mother to the fetus and its implications for the fetus were recognized by the teratogenic defects induced by thalidomide. In spite of the risk, there is a continuing need to receive medicines for genital infections (bacterial, yeast, viruses, etc.), epilepsy, diabetes, asthma and variety of other conditions during pregnancy. Small molecules (less than 600 Da) are known to transit the human placenta and reach the fetus by passive diffusion while the passage of substances of molecular weight >1000 Da may be restricted depending upon whether there are specific receptors on the surface of the syncytiotrophoblast to facilitate the movement of these large molecules. Nanodrugs continue to be a powerful factor in the advancement of clinical therapy. However, the potential clinical applications of nanodrugs warrant their investigation in terms of biodistribution and safety during pregnancy and lactation. Material and methods The literature was searched in bibliographic databases (PubMed, ScienceDirect) according to the primary keywords. Articles obtained by searching of the literature were classified from general to more specialized. Relevant articles are selected, and then examined in an analytical and critical way. The most important results, as well as own considerations are quoted in the overview. Results The materno-fetal transfer of nanomedicines has become of great interest in assessing their safety and the associated risk of growth and developmental defects in the fetus. Possible transport routes for nanoparticles across the placenta include diffusion, vesicular transport, transmembranal transporter proteins and the transtrophoblastic channel system. Placental structure, cellular composition, function and blood flow change with gestational age, which alters placental uptake and transport. Translocation of nanoparticles is likely to be dependent on the different stages of pregnancy. In the first trimester, the placental barrier is very thick in order to protect the developing embryo and becomes thin at term when substantial amounts of nutrients are required to sustain fetal growth. The size, surface charge and surface properties of nanoparticles is key parameters which influence placental/fetal penetration and biodistribution of nanoparticles. Besides understanding how nanoparticle characteristics influence placental transport, it will be essential to achieve a comprehensive insight into the mechanisms underlying this transfer. Conclusion The development of novel nanoparticle-based therapies in pregnancy and lactation requires an in-depth understanding of the mechanisms of placental nanoparticle transfer. Achieving a comprehensive understanding on how nanoparticle characteristics such as size, shape, charge, chemical composition and targeting ligands impact on placental accumulation, translocation and biological effects is central to the development of new drug-delivery systems with the objective to preferentially treat the mother, the fetus or placental disorders. In pregnancy, no nanomedical therapies have yet been established; however, the clinical need for improved drug delivery systems with high selectivity and safety is tremendous.