This was a community-based, descriptive cross-sectional study conducted over a period of three months (January to March 2025) in the Douala IV municipality, Littoral Region of Cameroon. Douala IV is a highly populated urban district comprising neighborhoods such as Bonaberi, Bépanda, and Mabanda, characterized by high youth density, school dropout rates, and limited access to youth-oriented reproductive health services.

The target population consisted of adolescents and young adults aged 15 to 24 years residing in Douala IV. Both males and females were included in the study, provided they had initiated sexual activity and consented to participate. The inclusion criteria required participants to be within the target age range, reside in the municipality for at least six months, and be available and willing to complete the questionnaire. Adolescents under 18 years were included after obtaining parental or guardian consent and participant assent. Individuals who were mentally or physically unable to respond to the questions were excluded.

Participants were adolescents and young adults aged 15 - 24 years who had initiated sexual activity and resided in the area for at least six months. Parental consent was obtained for minors. The sample size was calculated using Cochran’s formula for cross-sectional surveys. Parameters included an expected prevalence of 0.5 (to maximize sample size), a precision (margin of error) of ±5%, and a 95% confidence level. This yielded a minimum sample of 355 participants. To increase statistical power and account for potential non-response, the final sample was increased to 400.

A multi-stage stratified random sampling method was employed. First, the municipality was divided into health areas. Within each area, neighborhoods were randomly selected. From each selected neighborhood, households were visited using systematic sampling. One eligible participant per household was interviewed. To ensure representativeness, efforts were made to include both in-school and out-of-school youths, as well as those attending youth-friendly health centers.

A multi-stage stratified random sampling method was employed. First, the municipality was divided into health areas. Data were collected using a structured, pretested questionnaire developed in English and French. The tool included four sections:

The questionnaire was self-administered for literate participants and interviewer-administered for those requiring assistance. Six trained data collectors and two supervisors oversaw data collection, ensuring confidentiality and accuracy. A pilot test was conducted in a nearby municipality (Douala III) with 20 participants to validate the tool’s clarity and reliability. Necessary modifications were made prior to the main survey.

The composite score for contraceptive knowledge was developed from 10 items assessing awareness of modern contraceptive methods, with a total score range of 0 - 10. Scores below 5 were classified as “low knowledge”. Similarly, the parental communication score was based on 8 items evaluating frequency and openness of discussions on sexual and reproductive health, with scores below 4 considered “low communication”.

Collected data were coded, entered into Microsoft Excel, and exported to SPSS version 25.0 for statistical analysis. Descriptive statistics were used to determine frequencies and proportions. Chi-square tests were used to assess associations between categorical variables and outcomes (unintended pregnancy and STI symptoms). Binary logistic regression was performed to identify independent predictors of each outcome, with a significance threshold set at p < 0.05.

Ethical clearance was obtained from the Institutional Review Board of the Faculty of Health Sciences, University of Douala (Ref: 2024/074/UB/FHS/IRB). Administrative authorization was granted by the Douala IV Health District and local community leaders. Written informed consent was obtained from all participants aged 18 years and above. For minors, assent was obtained alongside parental consent. Participation was voluntary, and confidentiality was strictly observed throughout the study. No identifying information was recorded.

A total of 400 adolescents and young adults aged 15 to 24 years participated in the study. The majority were aged between 18 - 20 years (40%), followed by those aged 21 - 24 years (37.5%) and 15 - 17 years (22.5%) ( Table 1 ). Most respondents were single, with a roughly equal distribution of males and females.

Among female respondents, 32% reported having experienced at least one unintended pregnancy ( Table 2 ). The majority of unintended pregnancies occurred in the 20 - 24 age group, particularly among those who were no longer in school or had low knowledge of contraceptive methods.

Nearly half of the participants (45.5%) reported having experienced at least one symptom suggestive of a sexually transmitted infection (STI) in the past year. The most common symptoms were genital discharge (30%), painful urination (23.8%), and lower abdominal pain (21.2%). Genital sores were reported by 15% of respondents ( Table 3 ).

Risk factors significantly associated with STI symptoms included early sexual debut (25%), having multiple sexual partners (35%), inconsistent condom use (40%), and alcohol use before sex (22.5%) ( Table 4 ). Logistic regression analysis confirmed that multiple sexual partners (OR = 2.4, p < 0.01) and inconsistent condom use (OR = 3.1, p < 0.001) were strong independent predictors of reported STI symptoms.

The multivariable logistic regression analysis identified several independent predictors of unintended pregnancy among female respondents ( Table 5 ). Adolescents aged 20 - 24 years were significantly more likely to report an unintended pregnancy compared to those aged 15 - 17 years (AOR = 2.10, 95% CI: 1.15 - 3.85, p = 0.016). Being out of school (AOR = 1.95, 95% CI: 1.05 - 3.62, p = 0.034) and having low contraceptive knowledge (AOR = 2.45, 95% CI: 1.35 - 4.43, p = 0.003) were also associated with higher odds of unintended pregnancy. Although early sexual debut and low parental communication showed elevated odds, their associations did not reach statistical significance.

For reported STI symptoms, multiple behavioral and social factors remained significant after adjustment ( Table 6 ). Respondents with multiple sexual partners had more than twice the odds of reporting STI symptoms (AOR = 2.40, 95% CI: 1.45 - 3.98, p = 0.001), while inconsistent condom use was the strongest predictor (AOR = 3.10, 95% CI: 1.95 - 4.92, p < 0.001). Alcohol use before sex (AOR = 1.75, 95% CI: 1.02 - 3.00, p = 0.041) and low parental communication (AOR = 1.68, 95% CI: 1.01 - 2.81, p = 0.046) also significantly increased the likelihood of STI symptoms. Early sexual debut and low contraceptive knowledge showed positive but non-significant associations.

This study highlights significant reproductive health challenges among adolescents and young adults in Douala IV, where unintended pregnancy and sexually transmitted infections (STIs) remain pressing public health issues. The prevalence of unintended pregnancy (32%) and self-reported STI symptoms (45.5%) reflects a substantial burden, consistent with national estimates from the 2018 Cameroon Demographic and Health Survey ( Institut National de la Statistique & ICF, 2019 ) and global WHO data showing that adolescent girls face a disproportionate risk of early and unintended pregnancies ( UNFPA, 2020 ; WHO, 2022a ). High rates of STI symptoms, including genital discharge (30%) and painful urination (23.8%), also align with WHO’s concerns regarding youth sexual health in sub-Saharan Africa ( WHO, 2022b ; Ministère de la Santé Publique du Cameroun, 2023 ).

Behavioral factors play a central role in shaping these outcomes. Early sexual debut was reported by 25% of participants and is linked to lower contraceptive use and increased risk of both unintended pregnancy and STIs ( Kramer & Abenhaim, 2016 ). Inconsistent condom use (40%) and multiple sexual partnerships (35%) were common and emerged as strong predictors of STI symptoms, consistent with regional studies emphasizing unprotected sex, alcohol consumption (22.5% before sex), and multiple partnerships as key risk factors ( Chandra-Mouli et al., 2019 ; Diouf et al., 2020 ; Ndeh et al., 2021 ). These risky behaviors frequently co-occur in low-resource urban contexts like Douala IV, where adolescents face economic hardship, peer pressure, and limited social support.

Gender dynamics further exacerbate adolescent vulnerability. Coercive or transactional sexual relationships, particularly involving older or economically powerful partners, restrict adolescent girls’ ability to negotiate condom use, contributing to high rates of unprotected sex ( Jewkes & Morrell, 2010 ). Regression analyses confirmed that being aged 20 - 24 years, out of school, and having low contraceptive knowledge were significant predictors of unintended pregnancy. Meanwhile, inconsistent condom use and multiple sexual partnerships were the strongest predictors of STI symptoms. Alcohol use before sex and weak parental communication also increased risk, highlighting the combined influence of individual behaviors, gendered power relations, and family-level factors ( Kramer & Abenhaim, 2016 ; Ndeh et al., 2021 ).

Structural and systemic barriers reinforce these vulnerabilities. Many participants exhibited limited knowledge of contraception, indicating significant gaps in reproductive health education ( Tchouakam et al., 2020 ). Despite UNESCO and WHO recommendations for implementing comprehensive sexuality education (CSE) ( UNESCO, 2018 ; WHO, 2022a ), integration in Cameroon remains weak and inconsistent ( UNICEF Cameroon, 2020 ). Moreover, youth-friendly health services are inadequate, with adolescents often reporting judgmental attitudes, lack of privacy, and confidentiality breaches from healthcare providers ( Pathfinder International, 2019 ). These factors discourage them from seeking preventive care such as STI screening or contraceptive counseling. The socio-economic context of Douala IV—marked by urban poverty, unemployment, and limited recreational or counseling structures—further fuels risky sexual behavior among out-of-school and economically marginalized youth ( UN-Habitat, 2021 ).

The findings underscore the need for multisectoral interventions that address the behavioral, structural, and contextual determinants of adolescent reproductive health risks. Key priorities include scaling up comprehensive sexuality education ( UNESCO, 2018 ; UNICEF Cameroon, 2020 ), expanding access to confidential and youth-friendly reproductive health services ( Pathfinder International, 2019 ), and reinforcing community and parental involvement. Programs should also target gender-sensitive strategies that empower adolescents—particularly girls—to negotiate safer sexual practices. Additionally, policy frameworks should be effectively implemented and monitored to ensure alignment with evidence-based approaches ( Ministère de la Santé Publique, 2021 ). Promoting consistent condom use, reducing multiple sexual partnerships, and tackling gender-based vulnerabilities are critical to mitigating the burden of unintended pregnancy and STIs among adolescents and young adults in Douala IV.

This study has certain limitations. First, outcomes such as unintended pregnancy and STI symptoms were self-reported, which may be subject to recall bias and social desirability bias. Second, STI diagnoses were based on reported symptoms rather than laboratory confirmation, which could have led to misclassification. Finally, the cross-sectional design limits the ability to infer causal relationships between identified risk factors and outcomes.