Normal pregnancy and coagulation profile: from the first through the third trimester

Normal pregnancy is a hypercoagulable state; a physiological safety valve aimed at preventing excessive maternal blood loss at delivery.

To evaluate the influence of normal pregnancy on blood coagulation and to explore changes in activity from the first through the third trimester.

Sixty (60) apparently healthy pregnant women (20 from each trimester) and 20 healthy non-pregnant age-matched controls were recruited. Each participant had Prothrombin time (PT). Activated partial thromboplastin time (APTT) and platelet count done. Multiple comparisons were made between control values and coagulation profile at different stages of pregnancy using the Bonferroni statistics. Results were expressed as means and standard deviations, p < 0.01 was significant at 95 % CI. Ethical approval for the study was obtained from the Institutional review board.

The means of the APTT were significantly lower in the first, second and third trimesters compared with controls (35.59 ± 4.95 seconds, 32.22 ± 5.79 seconds and 29.60 ± 3.66 seconds, respectively, vs. 40.55 ± 5.95 seconds; p = 0.01). Correspondingly, the platelet count was significantly lower in the 3 trimester of pregnancy compared with controls (178.35 ± 41.52 x 10(9)/L vs. 233.86 ± 55.34 x 10(9)/L; p < 0.01) and equally with level in the 2nd trimester (178.35 ± 41.52 x 10(9)/L vs. 232.10 ± 48.67 x 10(9)/L; p < 0.01).

The APTT and platelet counts are significantly lower in the 3 trimester of normal pregnancy.