['To analyze the frequency of plasmacytoid dendritic cells (pDCs) in pregnancy, especially their subsets, by flow cytometry in each trimester and in the postpartum period.', 'Peripheral blood was collected from pregnant women in each trimester and from non-pregnant women. Serum hormones were detected by ELISA, while pDCs and their subsets were detected by flow cytometer. Then correlation between them was further analyzed.', 'Both pDCs and their subsets declined as pregnancy progressed. Further experiments indicate that estradiol and progesterone are significantly negatively correlated with this change.'] Do decline of Plasmacytoid Dendritic Cells and Their Subsets in Normal Pregnancy Are Related with Hormones?