Abstract
                 Background: Pregnancy is a period of reproduction during which a woman carries one or more live offspring from   implantation of a fertilized zygote in the uterus throughout gestation. There are several physiological changes that occur  in pregnancy. Physiology of a normal pregnancy involves major changes in both the coagulation system and hematological   parameters. These changes appear to be related to the development of the uteroplacental circulation and provide a   protective mechanism during delivery. Objective: To study the normal changes that occur to red blood cells (RBCs), white blood cells (WBCs), hemoglobin (Hb),  platelets, and hemostatic profile (prothrombin time [PT] and partial thromboplastin time [PTT]) among pregnant Sudanese  women and compare it within the three different trimesters. Materials and Methods: A total of 50 apparently healthy pregnant women (gestational age 6–40 weeks) with age range  between 20 and 40 years were recruited into the study. They were attending Khartoum teaching hospital, Khartoum,  Sudan. There were no special preparation for subjects or questionnaires, and direct interviews were used to collect  demographic and clinical data. After informed consent was obtained from the participants, 5 mL of venous blood was  subsequently collected from an antecubital vein, with the subject comfortably seated, into ethylenediaminetetraacetic acid  and citrate vacuum tubes. Hematological parameters including WBC, RBC, Hb, packed cell volume, and platelets were  measured by Sysmex. The plasma clotting time, PT, and PTT were measured manually. 3 Results: The hematological parameters were represented as follows: mean value of WBCs was 7.580 cell/mm , RBCs  12 9 was 4.1× l0 /L, Hb was 11.79 g/dL, platelets was 256 × 10 /L, PT mean value of the study group was 13.40 s, and PTT  was 36.20 s. Conclusion: There was no statistical significance in RBCs, Hb, platelets, PT, and PTT between pregnant women in the  three different trimesters, whereas WBCs count showed significant differences among the three groups, the highest value  was found in the second group followed by the third group and the lowest value found in the first group.