Leucocyte counts in pregnant Nigerian women with sickle cell trait.

White blood count (WBC) with differential counts and packed cell volume (PCV) were studied in 100 pregnant and 30 non-pregnant control women aged 18-45 years. Eighty of the pregnant women were homozygous HbAA and 20 heterozygous HbAS. The non-pregnant women's PCV, lymphocyte and eosinophils counts were significantly higher (p < 0.005) while their leucocytes neutrophil counts were significantly lower (p < 0.005) compared with HbAA and HbAS pregnant women. However, HbAS pregnant women had higher leucocyte, lymphocyte and eosinophil counts compared with HbAA, but these were not significant. There were no variations in basophil and monocyte counts. HbAA pregnant women had no change in PCV but significant changes occurred in leucocyte and neurophil counts with increase in the second trimester with decreasing lymphocyte and eosinophil counts in the second and third trimesters. However, HbAS pregnant women had significant increase in PCV in their first trimester, leucocyte and neutrophil counts in their third trimester but no variation in lymphocyte, eosinophil and basophil and monocyte counts. The increased leucocyte and neutrophil counts in the second trimester in HbAA and third trimester in HbAS may be due to genetic factor and/or oestrogen secretion reaching production peak at different periods of pregnancy. The relative increase in these haematological indices in HbAS women may be a protective mechanism against infection during pregnancy.