Aim: To obtain knowledge of the relationship between cell-free and exosomal pregnancy-associated microRNAs in maternal plasma, the authors investigated their circulating levels before and after amniocentesis. Materials and Methods: In 16 maternal plasma samples collected before and after amniocentesis, circulating levels of cell-free and exosomal pregnancy-associated microRNAs (miR-515-3p, -517a, -517c, -518b, and 323-3p) were measured by real-time quantitative RT-PCR. Changes in the plasma concentration and the association between circulating levels of cell-free and exosomal microRNAs were analyzed. Statistical significance was defined as p < 0.05. Results: The plasma concentration of cell-free miR-518b was significantly decreased after amniocentesis (Wilcoxon signed rank test, p = 0.001), but no significant difference was observed in any other cell-free or exosomal microRNA (p > 0.05). There was no association between the circulating levels of cell-free and exosomal microRNAs (miR-515-3p, -517a, -517c, -518b) in chromosome 19 microRNA cluster region. However, a significant association was detected between plasma cell-free and exosomal miR-323-3p levels in chromosome 14 microRNA cluster region (r and P values before amniocentesis; 0.617 and 0.011, those after amniocentesis; 0.899 and < 0.001). Conclusions: Amniocentesis caused a decreased cell-free but not exosomal miR-518b levels in maternal plasma. Correlations between plasma concentrations of cell-free and exosomal pregnancy-associated microRNAs were different for each microRNA.