Medium-dose intravenous immunoglobulin therapy for women with six or more recurrent miscarriages

•60-g IVIg therapy was administered for RM with six or more miscarriages.•NK cell activity decreased and monocyte percentage increased one week after therapy.•The live-birth rate in 14 RM women administered 60 g IVIg therapy was found to be 30.8%.

This study aimed to evaluate changes in natural killer (NK) cell activity and the percentage of monocytes in women with recurrent miscarriage who received medium-dose intravenous immunoglobulin (IVIg) therapy. Fourteen women with a history of six or more recurrent miscarriages of unexplained etiology received 60-g IVIg therapy (20 g daily, for three days) during early gestation. NK cell activity in the peripheral blood decreased to 12% one week after therapy compared with before therapy (median, 22%, P < 0.001) and the percentage of monocytes increased from 5.2% to 7.5% (P < 0.005). Four pregnancies ended in live births of healthy neonates, whereas the other ten pregnancies ended in miscarriages. Excluding one miscarriage with a chromosomal abnormality, the live birth rate was 30.8% (4/13). The rate of reduction of NK cell activity in the success group (−58.8%) tended to be greater than that in the failure group (−14.8%, P = 0.057).