High NK cell activity in early pregnancy correlates with subsequent abortion with normal chromosomes in women with recurrent abortion

PROBLEM: The aim of this study was to assess the role of natural killer (NK) cells in pregnant women with a history of recurrent spontaneous abortion (RSA). METHOD OF STUDY: Consecutive 66 pregnant women with a history of RSA were prospectively assessed for peripheral NK cell activity, percentage of the NK cell subsets, and subsequent pregnancy outcome. RESULTS: NK cell activity in women with subsequent live birth (group I) at 4-5 gestational weeks (GW) (mean +/- SD, 32.5 +/- 12.3%) significantly decreased at 6-7 GW (28.1 +/- 12.1%) and at 8-9 GW (28.0 +/- 11.8%). NK cell activity in women with subsequent abortion with normal chromosomes (group II) at 6-7 GW (41.2 +/- 19.0%) was significantly higher than that in group I women, while NK cell activity at 6-7 GW in women with subsequent abortion with abnormal chromosomes (group III) was the same as the level in group I women. CONCLUSIONS: High NK cell activity at 6-7 GW correlates with subsequent abortion with normal chromosomes.