[Changes of differential leukocyte counts during pregnancy and in the postpartum period]

We examined differential leukocyte counts in peripheral blood from 177 pregnant and postpartum women with an automated leukocyte differential system, and compared them with those of 52 nonpregnant and non-postpartum women. The proportions and numbers of neutrophils and monocytes increased throughout pregnancy, returned to the non-pregnant levels within one month after delivery, and decreased transiently at 4 or 7 to 10 months postpartum. The proportions and numbers of lymphocytes and eosinophils decreased throughout pregnancy, and increased transiently at 4 to 10 months postpartum and one month postpartum, respectively. The proportion and number of basophils decreased during pregnancy and one month postpartum, and those of large unstained cells (LUC) decreased in the third trimester of pregnancy, and both returned to the non-pregnant levels at 4 months postpartum and within one month postpartum, respectively. These data indicate that differential leukocyte counts change dynamically during pregnancy and after delivery until 1 year postpartum.