Pregnancy-induced leukocytosis in Yemenite Jews.

Benign neutropenia is often found among healthy Yemenite Jews. An assessment was made of the magnitude of labor-induced leukocytosis in 44 Yemenite Jewish women, by comparing their hematological values during labor with those of 27 non-Yemenite women. A statistically significant difference was found in the absolute counts of the white blood cells (WBC) during delivery between the two groups, the values being lower among Yemenite Jews [10,291 +/- 422] vs. [11,759 +/- 630] X 10(9)/1) and similar findings were detected among their infants. The low WBC counts in the Yemenite group at parturition were also associated with significantly lower plasma cortisol levels (Yemenite group: 33.7 +/- 3.5 micrograms/dl; controls: 49.3 X 2.9 micrograms/dl). A correlation was found between serum cortisol levels and the magnitude of leukocytosis in both groups of women and their infants. These results suggest that a low basal corticosteroid output may contribute to the low white blood cell counts detected in some ethnic groups like the Yemenite Jews.