Bohicon, a commune located in the Zou department, in the southern region of the Republic of Benin, covers an area of 139 km² and had a population of 171,781 in 2013 according to RGPH4. It is situated 130 kilometers away from Cotonou, the national capital. The local population is primarily Fon, representing 91.20% of the total population. Bohicon has 30 secondary institutions, including 10 public, 17 private, and 3 religious schools [12] .

This was a case-control study conducted from March 21st to April 2nd, 2022, in secondary and technical institutions in the commune of Bohicon.

Cases included adolescent girls aged 10 to 19, enrolled in a secondary or technical institution in the commune of Bohicon for the 2021-2022 academic year, and who became pregnant during the same school year. As for the inclusion criteria for controls, they encompassed adolescent girls of the same age group and enrolled in the same institutions, but who had never experienced a pregnancy at the time of data collection. Concerning the non-inclusion criteria, they applied to adolescents meeting the inclusion criteria but not providing informed consent, or not obtaining it from their parents (for those under 18) to participate in the study. The exclusion criteria excluded adolescents unable to continue the interview, irrespective of the reason, among both cases and controls.

Matching was done based on the institution and class at a ratio of one case to two controls. Cases were identified by counting the enrolled adolescent girls for 2021-2022 in secondary or technical institutions in the commune of Bohicon who became pregnant during the school year. For each identified case, two controls were randomly selected from the same institution and class, from the list of all adolescent girls in the same class who had never experienced a pregnancy until the day of data collection.

The dependent variable was “Early Pregnancies in the School Environment” with the categories “Yes” for cases and “No” for controls. Independent variables included sociodemographic characteristics (age, family type, birth order, marital status, place of residence, educational level, ethnicity, and religion), socioeconomic factors (monthly allowance, existence of a secondary source of income, household socioeconomic well-being level), environmental factors (peer influence, parental control, parent-child communication), biological factors (puberty), and factors related to behavior (age of the adolescent's first sexual intercourse, use of contraceptive methods, self-esteem, number of sexual partners).

Data collection techniques for cases and controls included surveys based on questionnaires designed by the research team, using a structured questionnaire as a tool, pre-tested previously in a secondary school in Abomey, located in the same department as Bohicon in order to verify its reliability and validity.

Data analysis was conducted in two stages using Stata 15. First, a descriptive analysis was performed to calculate the proportions or percentages of qualitative variables. Then, the evaluation of the adolescents socioeconomic status was based on a composite indicator of household economic well-being, developed using the Filmer method, considering various household characteristics and assets. This score was then divided into tertiles corresponding to low, medium, and high socioeconomic levels [13] . Parental educational practices were assessed using Claes et al.’s scales. “Parental Control” was measured using seven items scored from 1 to 4, with an expected maximum score of 28, a mean score of 17.5, and a minimum score of 7. The quality of parent-child communication was evaluated through five items scored from 1 to 4, with an expected maximum score of 20, a mean score of 12.5, and a minimum score of 5. Sufficiency or insufficiency thresholds were defined based on the mean score [14] . Self-esteem was measured using the Rosenberg scale, comprising ten statements evaluated from 1 to 4. Scores were calculated by adding the scores of statements A1, A2, A4, A6, and A7, while statements A3, A5, A8, A9, and A10 were reverse scored. Expected scores ranged from 10 to 40, and self-esteem was considered low or high based on the median score [15] . Regarding the analysis of data related to “monthly allowance of the adolescent,” a threshold of 10,000 CFA Francs was defined based on the distribution of collected data. This simplifying approach was adopted to facilitate analysis and comparisons. The analytical stage included univariate analysis using simple conditional logistic regressions to determine associations between the dependent variable and the independent variables, calculating the odds ratios with a 95% confidence interval [95% CI]. The significance level was set at 5%. Subsequently, multivariate analysis was performed with a multiple conditional logistic regression model to identify factors associated with early pregnancies in the school environment. Variables with a p-value less than 20% in univariate analysis were included in the initial model and then progressively eliminated. The final variables were those with a p-value less than 5%. Model adequacy was evaluated using the Hosmer-Lemeshow test, with reference categories identifying the lowest risk of pregnancy among adolescents.

Data entry and cleaning were done using Epi info 7.2.1.0 software. Data were analyzed using the STATA 15 software. Univariate analysis was used to describe the sociodemographic characteristics and factors associated with early pregnancies. The Chi-square test was used to compare the proportions between cases and controls, and the Student's test was used to compare the means. Bivariate analysis was used to assess the association between each independent variable and the dependent variable. Variables with a p-value ≤ 0.20 in the bivariate analysis were retained for the multiple conditional logistic regression analysis. The threshold of statistical significance was set at 5%. The results were presented in the form of tables and figures.

Prior to data collection, we obtained permission from the Departmental Director of Secondary Technical and Vocational Education of Zou, as well as from the directors of the various institutions. All individuals targeted were informed of the study’s objectives, and we obtained informed consent from the participants (or their parents for adolescents under 18 years old). To ensure confidentiality, data were collected in a closed room, preserving the anonymity of the respondents by associating each questionnaire with a number.

Table 2 shows the association between sociodemographic variables and the occurrence of early pregnancy. Among the socio-demographic variables, three were significantly associated with early pregnancy. These were age (p = 0.000), ethnicity (p = 0.012) and marital status (p = 0.000).

Table 3 presents the association between behavioural factors and the occurrence of teenage pregnancies.

Table 4 shows the association between socioeconomic variables and the occurrence of early pregnancy. The variable monthly pocket money was significantly associated with early pregnancy (p = 0.020).

The multivariate analysis revealed that age, marital status, and pocket money of the adolescent were associated with early pregnancies in the school environment in the commune of Bohicon in 2022 (Table 5).

One of the main challenges encountered during this study was the reluctance of authorities and adolescents, due to the sensitive nature of the subject addressing issues related to sexuality, often perceived as taboo, especially within family environments. Nevertheless, after clarifying the study's objectives and ensuring complete respect for anonymity and confidentiality, the participants finally agreed to collaborate. However, it is important to note that this research could be subject to certain biases, particularly regarding the selection of participants and the accuracy of the collected data. Some witnesses may have provided inaccurate information regarding their pregnancy history, which could introduce

selection bias. Additionally, information biases may be related, on one hand, to the sensitivity of the topics discussed (such as pregnancy and the sexual life of the interviewees) and, on the other hand, to the capacity for memory retention. Memory biases could be associated with questions regarding certain aspects such as the age of first sexual experience and the date of the last menstrual period. To mitigate these biases, preventive measures such as establishing a climate of trust and preserving the anonymity of responses were put in place. Despite these limitations, we believe that the conclusions of this study provide valuable insights to combat early pregnancies in schools in Benin.

Our observations on the mean age of cases and controls reveal interesting trends, which seem to be consistent with what has been previously documented in research conducted in similar geographical contexts. For example, a study conducted in Bamako in 2022 by Samaké and colleagues also revealed striking similarities regarding the average ages. They reported an average age of 17.4 years ± 1.2 for cases and 23.19 years ± 3.1 for controls [16] . Similarly, a study dating back to 2015, conducted by Glèlè et al. among adolescents living in the community in Lokossa, indicated a similar average age of 17.75 years ± 3.1 years [17] . Lastly, Mongbo et al., in a study conducted in Benin in 2018, obtained similar results, with an average age of 17.86 years. It is essential to note that out of the 47 early pregnancies recorded, 35 (74.46%) were reported in the upper cycle and 12 (25.54%) in the lower cycle. This trend could be attributed to the fact that senior adolescents, being closer to the end of their school career, may have fewer concerns about the potential impact of early pregnancy on their education. At the end of the cycle, they may be more willing to take risks in sexual behavior because they feel closer to adulthood and the end of their schooling. In addition, social or family pressures linked to academic success may be less restrictive for students at the end of the cycle, which can influence their behavior.

According to the findings of this study, the median age at first sexual intercourse was found to be 17 years for both cases and controls. This finding is consistent with the findings of Mongbo et al. as well as those of Abdourahamane et al., who reported an average age of 16 years in their respective studies conducted in Benin and Guinea [10] [18] . This similarity suggests a common trend that may be influenced by cultural and social norms. The age of 17 for the onset of sexual intercourse appears to indicate a critical transition to adulthood, often associated with the end of the schooling period. In many societies, cultural and social norms strongly surround the sexuality of young people, often imposing strict expectations regarding sexual behavior before a certain age. This social pressure can lead adolescents to postpone sexual initiation until they reach a certain stage of their education or personal development. However, once this critical period has passed, young people may feel freer to explore their sexuality and engage in intimate relationships. Social pressures related to academic achievement or family expectations can also play a significant role in this dynamic. For example, as young people approach the end of their schooling, they may feel less constrained to maintain strict sexual abstinence, which may explain the similarity observed in the median age of first sexual intercourse between cases and controls.

It was found that reaching the age of 16 or older among adolescent girls in the school environment increases the risk of early pregnancy in the commune of Bohicon by 1.72 times. At the age of 16, adolescents often enter a transition phase marked by a growing desire for independence and an exploration of their identity. This period generally corresponds to when young girls seek to better understand themselves, gain autonomy, and identify with the lifestyles of their peers. At this age, sexual characteristics develop, making them very attractive to young men. In many contexts, this period coincides with the time when young girls begin to express their sexuality and engage in romantic relationships. Similar findings were highlighted by Sidibé et al. in Guinea Conakry, who noted a significant increase in the risk of early pregnancy associated with the age of the adolescents [9] .

Unmarried adolescent girls included in this study had a higher risk of early pregnancy compared to those in free union. However, research conducted by Ayele et al. in northern Ethiopia, focusing on risk factors for early pregnancies, revealed that married adolescents were more likely to be pregnant than their unmarried counterparts (CI = 7.43 - 34.04) [19] . This disparity could be explained by the fact that early marriage is a widespread cultural phenomenon in Ethiopia, affecting nearly half of the adolescents [20] , whereas it is less common in Benin [21] . In many societies, early marriage is deeply rooted in cultural and social norms, and in Ethiopia in particular, it is widespread, affecting a considerable percentage of adolescent girls. The socio-cultural pressures that encourage early marriage can influence the dynamics of sexual relationships among married girls, prompting them to adopt more cautious behaviors and potentially restrict the number of sexual partners. In contrast, in Benin, where early marriage is less common, adolescent girls in common-law relationships may be less inclined to conform to the strict norms associated with a formal partnership, potentially exposing them to riskier behavioral situations, such as relationships with multiple sexual partners. Complex socio-cultural dynamics and contextual pressures may also influence individual perceptions of sexuality and romantic relationships, modulating the sexual and reproductive behaviors of adolescent girls in these different contexts.

The results of this study show that adolescent girls with low monthly income have an increased risk of early pregnancy in the commune of Bohicon. This finding is consistent with that of Ayele et al., who also found an association between the low socioeconomic level of adolescents in terms of pocket money and the occurrence of pregnancies in the school environment [18] .

Indeed, the economic pressures faced by adolescent girls, particularly those from disadvantaged backgrounds, can exert a significant influence on their relationship decisions and behaviors. The daily struggle to meet their basic needs can make adolescent girls vulnerable to offers of financial or material support from potential partners, even if these offers come with Frequency. Gifts and financial incentives can represent a form of security or comfort for these girls, temporarily alleviating the economic difficulties they face. In such circumstances, teenage girls may be more inclined to accept advances or enter into intimate relationships without the necessary precautions, exposing them to an increased risk of unwanted pregnancy. Economic insecurity can also limit their access to reproductive health information and services, depriving them of adequate education on contraception and safe sex practices. These precarious socio-economic conditions create an environment conducive to adolescent vulnerability, exposing them to situations where their choices are often influenced by immediate subsistence considerations rather than long-term planning.