Total and differential leukocyte counts percentiles in normal pregnancy

To establish leukocyte count and leukocyte differential percentiles in normal uncomplicated pregnancy.

This retrospective longitudinal study was performed in an outpatient facility for routine antenatal care. The study population comprised of 726 healthy women from the 5th to the 41st week of pregnancy. Altogether, there were 1749 complete blood count evaluations, of which 481 were in the 1st trimester, 687 in the 2nd trimester and 581 in the 3rd trimester. The total and differential leukocyte counts were determined by an automated cell counter.

The leukocyte and neutrophil counts gradually and significantly increased form the 1st to the 3rd trimester. The monocyte count increase became significant only during the 3rd trimester. The eosinophil count did not significantly change throughout pregnancy. The basophil count significantly decreased during the 2nd trimester and returned to 1st trimester values during the 3rd trimester.

In this study, we provide total and differential leukocyte counts' mean+/-S.D., minimal and maximal values, and the 3rd, 5th, 10th, 50th, 90th, 95th, and 99th percentiles for entire pregnancy and for each trimester separately. These reference values should prove useful for diagnostic and research purposes.