Assessment of protein C antigen, free protein S, and protein C activity in pregnancy: A cross-sectional study of pregnant Nigerian women

Introduction: With increasing evidence of thromboembolic events among pregnant Nigerian women and associated high maternal mortality rates, there is a need to document the plasma levels of some markers of thrombosis in this population to aid prompt management of thromboembolic events. Objectives: To determine the plasma levels of free protein S (fPS), protein C (PC) antigen (PCAg), and PC activity (PCAc) in normal pregnancy, and any correlations with maternal age, gestational age (GA), and blood group. Materials and Methods: A cross-sectional study of eligible pregnant women receiving antenatal care in a tertiary hospital in south-south Nigeria. The plasma concentrations of fPS, PCAg, and PCAc were measured using enzyme-linked immunosorbent assay and Protac methods. Statistical analysis was both descriptive and inferential and done using SPSS, version 21, for windows. A P-value of <0.05 was considered statistically significant. Results: Eighty pregnant women at a GA of 25–42 weeks (mean 35.4 ±5.2) were recruited with a mean age of 30.4 ± 5.1 years. The mean plasma levels and range of fPS, PCAg, and PCAc were 47.2 ± 10.3%, 77.5 ± 23.2% and 110.4 ± 27.6%, respectively. There were significant positive correlations between PCAg and GA (r = 0.229, P = 0.041), PCAc and GA (r = 0.223, P = 0.046), and fPS and maternal age (r = 0.254, P = 0.023). Conclusion: Plasma concentration of PCAg and PCAc increased as pregnancy advanced, although fPS was below the reference limit, it increased with advancing maternal age. This information should be considered while evaluating pregnant women.