The three trimesters of pregnancyinclude various changes in digestive system, nutrition and metabolism, changes in circulatory system, respiratory system,integumentary system, changes in coagulation, and fibrinolysis which is beenexplained in various studies. Nearly, allorgan systems undergo profound changes during normal pregnancy to meet the demandsof the fetoplacental unit.
There are both subtle and substantial changes inhematological parameters during pregnancy and the puerperium, orchestrated bychanges in the hormonal milieu. A thorough understanding of these is important to avoid both over- and under-diagnosing abnormalities. During pregnancy, the total volumeof blood increases by about 1.5 L, mainly to supply the needs of the newvascular bed. Nearly, 1 L of blood is contained within the uterus and maternalblood spaces of the placenta.
Almost 25–80% of plasma volume gets expandedduring mid-pregnancy. Red cell mass also gets increased by 10–20% with the netresult in fall of hemoglobin (Hb) concentration.1 Red blood cell (RBC) mass beginsto increase at 8–10 weeks of gestation and steadily increases by 20–30% (250–450mL) above non-pregnant levels by the end of pregnancy in thosewomen who were receiving ironsupplements.2,3 Among women who werenot on iron supplements, the red cell mass may increase only by 15–20%.
4 Erythrocyte life span is slightly decreasedduring normal pregnancy.5 There is increase inerythropoietin level by 50% in normal pregnancies and vary according to thepresence of pregnancy complications.6 Increased plasma erythropoietin induces the rise in red cell mass, which partiallysupports the higher metabolic requirement for oxygen during pregnancy.7 Mean corpuscular volume decreases duringpregnancy and averages 80–84 fL in the third trimesterof pregnancy.8 White blood cell count (WBC) is increased in pregnancy with a typical reference range of 6 × 109–16 ×109/L.
9 Withinfew hours after delivery, healthy women have been documented to have WBC countof 9 × 109–25 × 109/L.10 By 4-week postdelivery, typical WBC ranges are similar to those inhealthy non-pregnant women (4 × 109–10× 109/L). There has been muchdiscussion about the normal ranges for the different types of white cells.
11 The present study was done to evaluate the variations in RBCand WBC counts before and after normal vaginaldelivery.