Clinical Research in Urology • Vol 3 • Issue 2 • 2020 1 INTRODUCTION The hemostatic balance tilts in the direction of hypercoagulability which helps to reduce bleeding complications during delivery. [1] The changes in the coagulation system during normal pregnancy are consistent with a continuing low-grade process of intravascular coagulation. [2] The hormones which are necessary for the maintenance of pregnancy, that is, estrogen and progesterone increase several folds and these, especially estrogen stimulate hepatocytes thereby increasing the production of virtually all coagulation factors. Evaluation of levels of certain coagulation factors occur in practically all healthy pregnant women which are most likely the result of small amounts ORIGINAL ARTICLE Prothrombin Time and Activated Partial Thromboplastin Time in Pregnant Women Attending Antenatal Clinic at Nnamdi Azikiwe University Teaching Hospital (Nauth), Nnewi, Nigeria – A Cohort Study Aloy -AmadiOluchi 1 , Akujobi Augustine 2 , Nnodim Johnkennedy 1 , Nwadike Constance 1 , Edward Ukamaka 1 , Nwanguma Eberechi 1 1 Department of Medical Laboratory Science, Imo State University, Owerri, Imo State, Nigeria, 2 Department of Optometry, Imo State University, Owerri, Imo State, Nigeria ABSTRACT Background: Normal pregnancy is associated with major changes in many aspects of hemostasis, all contributing to maintain placental function during pregnancy and to prevent excessive bleeding during delivery. Most of these changes in blood coagulation create a state of hypercoagulability. The purpose of this study was to evaluate the values of prothrombin time (PT) and activated partial thromboplastin time (APTT) during normal pregnancy. Methods: This was a cohort study carried out at the antenatal clinics of Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria, from January to December, 2016. This research was carried out on 160 apparently healthy pregnant women who presented for booking for antenatal care in their first trimester. Their ages ranged from 20 to 40 years. Similarly, 160 age-matched females consisting of health science students and the staff of NAUTH, constituted the control group. These pregnant women were followed up till the last trimester, but only 140 subjects completed the study. Blood samples collected for PT and APTT were analyzed using standard laboratory methods. Results: The mean value of PT in the control subjects (14.68 ± 1.07) was significantly increased when compared with the first trimester (12.86 ± 1.29), second (11.74 ± 1.41), and third (10.96 ± 1.50) (F = 300.9, P = 0.000). The mean value of APTT in the control subjects was also significantly increased compared with the first trimester (30.10 ± 4.49), second (29.33 ± 4.59), and third (28.33 ± 4.76) (F = 24.1, P = 0.000). When compared among the trimesters, the mean value of PT was significantly shortened from the first (12.86 ± 1.29) to the third (10.96 ± 1.50) (F = 93.4, P = 0.000). There was also a significant shortening of APTT from the first trimester (30.10 ± 4.49) to the third (28.33 ± 4.76) (F = 7.6, P = 0.001). Conclusion: This study has shown that pregnancy shortens PT and APTT. This effect helps to prevent excessive maternal bleeding during delivery. Therefore, early evaluation of these parameters is encouraged to monitor pregnancy and prevent pregnancy complications. Key words: Activated partial thromboplastin time, Nigeria, Nnewi, pregnancy, prothrombin time Address for correspondence: Dr. Aloy -AmadiOluchi, Department of Medical Laboratory Science, Faculty of Health Science, Imo State University, Owerri, Nigeria, Tel:+2348037424672. © 2020 The Author(s). This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.0 license.