Drug delivery systems, drugs are administered into the amniotic fluid, may contribute to fetal therapy. The present study explored changes in the volume of amniotic fluid from E11.5 through E17.5, and kinetics of calcein-containing liposomal particles incubated in the amniotic fluid collected at E12.5, E14.5, and E16.5 in Jcl/ICR mice. The volume of amniotic fluid increased until E15.5, followed by a sharp decrease at E17.5. The calcein release rate remained within 4% until day 14 in serum and each amniotic fluid. No significant differences were noted in the release rate between the serum and amniotic fluid at various time points. Therefore, the calcein release rate of liposomal nanoparticles in the amniotic fluid remained low and did not differ from that in the serum for as long as 14 days at different time points during gestation. These observations suggest that liposomal nanoparticles remain stable for prolonged periods in the amniotic fluid.