This prospective analytical case-control study was conducted over a six-month period (January 2025 to June 2025) in Ebolowa, Cameroon, at two major public healthcare facilities: the Ebolowa Regional Hospital (ERH) and the Ebolowa Regional Hospital Center (ERHC). These institutions provide family planning services and possess laboratory infrastructure suitable for hemostatic analysis.

Women aged 18 - 45 years attending these facilities for any reason were eligible. Cases were women who had been using hormonal contraception for at least three months, while controls were women who had never used hormonal contraceptives. Pregnant women, those with known chronic hematological disorders, or those receiving anticoagulants, corticosteroids, or other medications affecting hemostasis were excluded. Non-compliant or pre-analytically compromised samples were also excluded.

Sociodemographic and clinical data were collected using a structured face-to-face questionnaire, including age, marital status, education level, occupation, lifestyle habits (such as smoking), medical history, body mass index and contraceptive practices.

Blood samples were collected and laboratory analysis carried out at the laboratory of the ERHC and the ERH by trained laboratory professionals, working under medical and regulatory oversight. Venous blood (4 - 5 mL) was collected from each participant into EDTA tubes for full blood count (hemoglobin and platelet count) and 3.2% sodium citrate tubes for coagulation tests (PT, aPTT, INR). EDTA samples were analyzed within 30 minutes. Citrated samples were centrifuged, aliquoted, frozen (−20˚C to −70˚C), and later thawed at 37˚C prior to analysis. Frozen plasma samples were transported on dry ice and analyzed within 4 hours, avoiding excessive agitation.

Hemostatic assays were performed using a STAGO automated analyzer with manufacturer-recommended reagents. Reference values were: hemoglobin ≥ 12 g/dL; platelets 150 - 400 G/L; PT 70 - 100%; aPTT ~35 s; INR 0.8 - 1.2.

Data were analyzed using SPSS version 25. Quantitative variables were expressed as mean ± standard deviation, and qualitative variables as frequencies and percentages. Group comparisons were performed using Student’s t-test, chi-square test, or Fisher’s exact test as appropriate. Odds ratios were calculated to estimate the association between hormonal contraceptive use and selected abnormal hemostatic parameters. Statistical significance was set at p < 0.05.

The study received ethical approval from the Regional Ethics Committee for Human Health Research of the South Region. Written informed consent was obtained from all participants, and data confidentiality was strictly maintained.

A total of 210 women were enrolled in the study, including 75 hormonal contraceptive users (cases) and 135 non-users (controls), corresponding to 36% and 64% of the sample, respectively, yielding a case-to-control ratio of approximately 1:2.

The mean age of participants ranged from 18 to 45 years.

Age distribution differed significantly between the two groups (p = 0.0001). Women aged 25 - 34 years constituted the largest proportion of hormonal contraceptive users (46.5%), whereas non-users were predominantly younger, with 80% aged between 18 and 24 years. This finding indicates that hormonal contraception was more frequently used by women in the mid-reproductive age group.

Table 1. Matching of cases and controls by socio-demographic data in a study on the hemostatic profile of women using hormonal contraception carried out in two hospitals in Ebolowa-Cameroon, 2025.

Marital status did not differ significantly between users and non-users (p = 0.5826). Single women represented 37.3% of contraceptive users and 62.7% of non-users, while married women accounted for 32.4% of users and 67.6% of controls. Similarly, religious affiliation showed no statistically significant association with contraceptive use (p = 0.6515), with Catholics being the predominant group in both populations.

In contrast, occupation was significantly associated with hormonal contraceptive use (p = 0.0109; Cramer’s V = 0.207). Students were underrepresented among users (26.5%) compared with controls (73.5%), whereas self-employed and salaried women exhibited higher proportions of contraceptive use. This suggests that socio-economic autonomy may influence access to and acceptance of hormonal contraception (see Table 1).

Combined estrogen-progestin oral contraceptives (COCs) were the most frequently used method, accounting for 26 women (34.7%). Among progestin-only methods, injectable contraceptives were predominant, with Sayana Press used by 21 participants (28.0%) and Depot Provera by 12 participants (16.0%), together representing 44.0% of the study population. Progestin implants were less commonly used, with Jadelle and Implanon NXT accounting for 12.0% and 8.0%, respectively. In contrast, use of the hormonal intrauterine device was rare, reported in only 1 participant (1.3%). Overall, the distribution indicates a predominance of systemic hormonal contraceptive methods, particularly injectables and combined oral contraceptives, among our studied population (see Table 2).

Table 2. Frequencies by type of contraceptive in a study on the hemostatic profile of women using hormonal contraception carried out in two hospitals in Ebolowa-Cameroon, 2025.

The comparative analysis of biological parameters revealed significant differences between hormonal contraceptive users and non-users.

3.3.1. Hemoglobin Level

The mean hemoglobin concentration was significantly lower among hormonal contraceptive users compared with controls (10.8 ± 1.39 g/dL vs 11.3 ± 1.70 g/dL; p = 0.0159). Although both values indicate a generally mild reduction, this finding suggests a higher prevalence of anemia among contraceptive users (see Table 3).

Table 3. Effect of Hormonal Contraception on Hemostatic Parameters in a study on the hemostatic profile of women using hormonal contraception carried out in two hospitals in Ebolowa-Cameroon, 2025.

3.3.2. Platelet Count

Platelet counts were significantly elevated in hormonal contraceptive users (402 ± 160 G/L) compared with non-users (271 ± 106 G/L; p < 0.0001). A substantial proportion of users exhibited platelet values near or above the upper limit of normal, indicating a relative thrombocytosis associated with hormonal exposure (see Table 3).

3.3.3. Coagulation Parameters

Prothrombin time (PT) was significantly increased among users (97.9 ± 12.9%) compared with controls (81.1 ± 18.8%; p < 0.0001).

The international normalized ratio (INR) was significantly higher in hormonal contraceptive users (1.19 ± 0.21) than in non-users (1.03 ± 0.09; p < 0.0001), reflecting alterations in coagulation balance.

Activated partial thromboplastin time (aPTT) was also significantly prolonged in users (37.5 ± 6.98 seconds) compared with controls (32.9 ± 2.15 seconds; p = 0.0223). The overall mean aPTT was 34.5 ± 17.8 seconds, with an average prolongation of approximately 5 seconds among users. The odds ratio for prolonged aPTT among users was estimated at 8.38 (95% CI: 4.39 - 16.0) (see Table 3).

Collectively, these findings indicate significant modifications of both intrinsic and extrinsic coagulation pathways associated with hormonal contraceptive use.

Analysis by contraceptive method revealed variability in hematological and hemostatic profiles.

Hemoglobin levels were lowest among users of combined oral contraceptives (9.49 ± 1.30 g/dL), suggesting a higher frequency of anemia in this group. Conversely, the highest hemoglobin values were observed among Sayana Press users (11.04 ± 1.31 g/dL).

Platelet counts were markedly elevated among users of Depot Medroxyprogesterone Acetate (447.62 ± 146.25 G/L) and combined oral contraceptives (438.50 ± 184.46 G/L), indicating a stronger platelet response associated with these methods. The lowest platelet counts were observed among hormonal intrauterine device users, although interpretation is limited by the very small sample size.

Prothrombin time was lowest among combined oral contraceptive users (69.83 ± 16.01%), whereas the highest PT values were recorded among hormonal IUD users.

INR values were highest among users of combined oral contraceptives (1.30 ± 0.19) and Implanon NXT (1.27 ± 0.22), indicating a relative imbalance in coagulation homeostasis. aPTT was most prolonged among users of combined oral contraceptives and Depot Provera, while shorter aPTT values were observed among Implanon NXT users.

These results highlight method-dependent effects of hormonal contraception on hemostatic parameters (see Table 4).

Table 4. Biological parameters by type of Contraceptive in a study on the hemostatic profile of women using hormonal contraception carried out in two hospitals in Ebolowa-Cameroon, 2025.

The study population was predominantly composed of young women aged between 18 and 35 years. This age distribution is in line with data from the 2018 Cameroon Demographic and Health Survey, which indicates that modern contraceptive methods are mainly used by women of reproductive age living in urban areas [2]. Women aged 25 - 34 years constituted the largest proportion of hormonal contraceptive users (46.5%), whereas non-users were predominantly younger, with 80% aged between 18 and 24 years, as this age could be a major confounding factor in this study for age has a significant and well-documented influence on hemostatic parameters (coagulation, anticoagulation, and fibrinolysis). Overall, aging is associated with a prothrombotic shift—often described as a state of “hemostatic imbalance toward hypercoagulability.” [5]. The relatively high proportion of students and salaried women further reflects the influence of educational attainment and socioeconomic status on contraceptive uptake, as previously documented in Cameroon and other sub-Saharan African countries [10][13].

In terms of marital status, the predominance of unmarried women among contraceptive users supports the growing trend of contraceptive use outside marriage. This pattern has been widely reported in Cameroon and reflects increasing reproductive autonomy among women, particularly those with higher levels of education and access to reproductive health information [9][11][16][23].

The predominance of combined oral contraceptives and injectable methods observed in this study reflects national trends reported by the Demographic and Health Survey, which identified injectable contraceptives as the most commonly used modern method in Cameroon [2]. Although implants were less frequently used, their uptake is gradually increasing through reproductive health initiatives supported by international organizations.

Previous studies in Cameroon have shown a preference for injectable contraceptives in urban areas, while oral contraceptives remain more common in rural settings [31]. The present findings align with these observations and highlight the importance of accessibility, counseling, and health system capacity in shaping contraceptive choices.

4.3.1. Hemoglobin Levels

Hormonal contraceptive users exhibited a modest but statistically significant reduction in hemoglobin concentration compared with non-users. Similar findings have been reported in studies conducted in Nigeria, Ethiopia, and Cameroon, suggesting that hormonal contraception may be associated with mild alterations in erythropoietic balance [25][27][31].

This reduction may be related to the systemic effects of certain hormonal components, particularly progestins, which have been implicated in subtle changes in erythropoiesis or iron metabolism [20][21]. Importantly, the magnitude of the decrease observed in the present study remained within a subclinical range and did not indicate a high risk of clinically significant anemia, consistent with observations reported in the Democratic Republic of Congo [32].

4.3.2. Platelet Count

A significant increase in platelet count was observed among hormonal contraceptive users. This finding is consistent with several studies conducted in West and Southern Africa, which reported higher platelet counts among women using hormonal contraceptives [25][28]-[30].

This absolute thrombocytosis may reflect a compensated biological response to estrogen-induced changes in coagulation pathways. Estrogens are known to enhance hepatic synthesis of procoagulant proteins and may contribute to increased platelet production or turnover [14][18]. Previous studies have demonstrated that combined hormonal contraceptives influence multiple components of the hemostatic system, including fibrinogen and coagulation factors VII and VIII [14][18].

4.4.1. Prothrombin Time and International Normalized Ratio

In the present study, hormonal contraceptive use was associated with an increase in prothrombin time and a concomitant decrease in INR values. These findings are consistent with reports from Nigerian cohorts, where similar coagulation profiles were observed among users of combined oral contraceptives [24].

Such changes likely reflect the procoagulant effects of estrogenic components, which promote increased synthesis of fibrinogen and vitamin K-dependent coagulation factors, particularly factors VII and X [15][17]. The observed pattern suggests a shift in coagulation balance rather than overt pathological disruption, indicating physiological adaptation of the extrinsic pathway.

4.4.2. Activated Partial Thromboplastin Time

Unlike prothrombin time, activated partial thromboplastin time (aPTT) was significantly prolonged among hormonal contraceptive users. Prolongation of aPTT may indicate adaptive modulation of the intrinsic coagulation pathway, potentially related to relative factor consumption or mild alterations in endogenous anticoagulant systems such as protein C or antithrombin [17][32][33].

Comparable findings have been reported in studies from Ethiopia, South Africa, and Nigeria, which documented stable prolongation of aPTT among women using hormonal contraceptive methods [26]-[28].

4.4.3. Integrated Interpretation of the Hemostatic Profile

Overall, the findings suggest a trend toward a compensated procoagulant state, characterized by elevated platelet counts, shortened prothrombin time, increased INR, and prolonged aPTT. This profile is consistent with international evidence describing hormonal contraceptive-induced changes in hemostasis mediated by increased fibrinogen levels, elevated coagulation factors VII, VIII, and X, and reduced functional activity of protein S [14][15][17].

Importantly, the observed alterations were moderate and did not reach pathological thresholds. This supports findings from African studies indicating that, despite measurable biological changes, the absolute risk of thromboembolic events among African women using hormonal contraception remains relatively low compared with that reported in European populations [26][28][30].

Consistent with existing literature, the biological effects observed in this study appear to vary according to contraceptive formulation. Estrogen-containing methods tend to induce more pronounced hemostatic changes than progestin-only methods [19][29][33][34]. The increased platelet counts and prolonged aPTT observed among long-term users support this hypothesis.

Although hormonal contraception remains a safe and effective family planning strategy in Cameroon, the findings of this study support the need for targeted clinical vigilance. Minimal hemostatic monitoring may be beneficial for women with additional thrombotic risk factors, while progestin-only methods should be preferentially considered for women with a history of thromboembolic disease, obesity, or smoking habits [22][23].