Early Sex and HIV Risk in Young Cameroonians: Motherhood Sharpens the Danger

In Cameroon, adolescent girls and young women carry a burden of HIV that remains nearly double that of their male peers, a disparity that has persisted across years of surveillance and prevention campaigns. A new analysis of national survey data now adds a crucial layer of nuance to this picture: the timing of a young woman’s first sexual encounter, and whether or not she has become a mother, appear to interact in ways that dramatically reshape her risk of infection. The study, published in BMC Infectious Diseases, draws on the 2017–2018 Cameroon Population-based HIV Impact Assessment, known as CamPHIA, one of the most comprehensive bio-behavioral surveys ever conducted in the country. Its findings suggest that prevention strategies which treat young women as a single homogeneous group may be missing the very subsets of that population who face the greatest danger.

The research team, led by Ololade Julius Baruwa of the University of Fort Hare in South Africa, together with Oluwaseyi Dolapo Somefun of the University of the Western Cape and Hlengiwe Gwebu of the University of Fort Hare, analyzed records from 4,825 adolescent girls and young women aged 15 to 24 years. CamPHIA is a household-based survey that combines structured interviews with laboratory testing for HIV, which means the outcome measure is not self-reported status but actual biomarker-confirmed infection. This distinction matters enormously in HIV research, because self-reported status is known to be unreliable, particularly among young people who may not have been tested recently or who may be reluctant to disclose a positive result. By anchoring the analysis in laboratory-confirmed serostatus, the study sidesteps one of the most persistent sources of bias in sexual behavior research.

The central exposure of interest was early sexual debut, defined as first sexual intercourse before the age of 15. Among the surveyed population, 10.5 percent of young women reported such an early debut, while 36 percent were already mothers. Overall HIV prevalence in the sample stood at 2 percent, a figure that conceals wide variation across subgroups. The investigators used weighted descriptive statistics to characterize the population and then moved to logistic regression modeling, the standard epidemiological tool for estimating the association between an exposure and a binary outcome such as HIV infection. Univariable models were fitted first, followed by multivariable models that adjusted for a range of potential confounders, allowing the researchers to isolate the contribution of early sexual debut from other characteristics that travel with it, such as age, schooling, and employment status.

The headline result was sobering but not unexpected: early sexual debut was associated with significantly higher odds of HIV infection, with an adjusted odds ratio of 1.86 and a 95 percent confidence interval spanning 1.08 to 3.20. In practical terms, young women who began sex before age 15 had nearly twice the odds of laboratory-confirmed HIV infection compared with those who debuted later, after accounting for other measured differences between the groups. The biological rationale for such an association is well established in the literature. The adolescent cervix has a zone of immature columnar epithelium, sometimes called cervical ectopy, that is more susceptible to microtrauma and to the passage of the virus. Early debut also extends the cumulative duration of sexual exposure over the life course, and it frequently correlates with partnerships with older partners, inconsistent condom use, and reduced negotiating power, all of which independently elevate risk.

Two other independent risk factors emerged from the multivariable models. Young women aged 20 to 24 had higher odds of infection than those aged 15 to 19, with an adjusted odds ratio of 1.95, a pattern that simply reflects the cumulative nature of sexual exposure with age. More striking was the finding that being neither in school nor employed was associated with roughly double the odds of infection, with an adjusted odds ratio of 2.02. This socioeconomic signal underscores a theme that HIV researchers have emphasized for decades: the epidemic among young women in sub-Saharan Africa is not driven by behavior alone but by the structural conditions that shape what choices are available in the first place. A young woman who has left school and cannot find work occupies a social position in which transactional relationships, age-disparate partnerships, and dependence on older partners become more likely, each of which carries elevated transmission risk.

The most novel contribution of the study, however, lies in its treatment of motherhood. Rather than simply adjusting for parity as a confounder, the investigators formally tested whether motherhood modified the association between early sexual debut and HIV infection. In statistical terms, they included an interaction term between the two variables in the regression model. The result was dramatic: the interaction carried an adjusted odds ratio of 9.78, with a 95 percent confidence interval of 4.52 to 21.26, providing strong evidence that the effect of early debut on HIV risk is not uniform across motherhood status. Effect modification of this magnitude is rare in observational epidemiology, and it signals that the pathways linking early sexual initiation to infection operate very differently for young mothers than for their nulliparous peers.

To translate the interaction into more interpretable quantities, the researchers generated adjusted predicted probabilities of HIV infection for each combination of motherhood and debut timing. The numbers tell a vivid story. Young mothers who had experienced early sexual debut faced a predicted infection probability of 4.05 percent, more than double the 1.69 percent seen among mothers who debuted later. Most striking of all, young women who had debuted early but had never given birth showed a predicted probability of just 0.39 percent, roughly a tenth of the figure for early-debuting mothers. This pattern suggests that early debut alone does not seal a young woman’s fate; it is the combination of early initiation and subsequent motherhood that marks the highest-risk trajectory. The authors propose several plausible mechanisms. Young mothers may face economic pressure that pushes them into transactional or age-disparate relationships, may experience interrupted schooling that limits health literacy and access to services, and may encounter judgment from health providers that discourages consistent engagement with HIV testing and prevention.

The sensitivity analyses added an important note of scientific caution. When the models were re-estimated under alternative specifications, the main association between early sexual debut and HIV infection was attenuated, losing some of its statistical strength. Yet the evidence for interaction with motherhood persisted. This pattern is instructive for readers trying to interpret the findings responsibly. The precise magnitude of the early-debut effect may be somewhat unstable, sensitive to how confounding is handled and how variables are coded, but the central insight, that motherhood fundamentally reshapes the risk landscape, appears robust. In epidemiological terms, the interaction is the more reliable signal, and it is the one with the clearest programmatic implications.

Those implications point toward integration rather than fragmentation. The authors argue for HIV and sexual and reproductive health services that are designed together rather than delivered in parallel silos, with particular attention to young mothers, a group that often falls between pediatric, adolescent, and adult services and slips through the gaps. Concretely, this could mean offering HIV testing and pre-exposure prophylaxis at antenatal, postnatal, and immunization visits, ensuring that young mothers who return to clinics for their children are systematically screened and supported for their own health. It also means protecting the educational and economic pathways that the data show to be protective: keeping girls in school, supporting young mothers to return to education, and creating employment opportunities that reduce the economic pressures driving risky partnerships. The study received no dedicated funding, and the authors used language-editing tools only for proofreading, with all content reviewed and approved by the research team.

Limitations deserve honest acknowledgment. The survey captured sexual debut through self-report, and retrospective reports of first intercourse are vulnerable to recall error and social desirability bias, particularly in settings where early sex carries stigma. The cross-sectional design of CamPHIA means that the temporal ordering between some factors and infection cannot be fully established, and unmeasured confounders, from partner characteristics to community-level prevalence, may contribute to the observed associations. The authors themselves note that the early-debut association weakened in sensitivity analyses. Even so, the persistence of the motherhood interaction across models, the use of biomarker-confirmed HIV status, and the large nationally representative sample combine to make this a study that prevention planners in Cameroon and across the region should take seriously. For the roughly one in three young Cameroonian women who are mothers, the message is that their vulnerability is not a fixed attribute but a modifiable one, shaped by the services, schooling, and economic options that societies choose to provide.

Subject of Research: The association between early sexual debut and HIV infection among adolescent girls and young women in Cameroon, and the modifying role of motherhood

Article Title: Association between early sexual debut and HIV infection among adolescent girls and young women in Cameroon: does motherhood modify the relationship?

Article References: Baruwa, O. J., Somefun, O. D., & Gwebu, H. (2026). Association between early sexual debut and HIV infection among adolescent girls and young women in Cameroon: does motherhood modify the relationship?. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14608-5

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14608-5

Keywords: HIV, adolescent girls and young women, early sexual debut, motherhood, Cameroon, CamPHIA, epidemiology, sexual and reproductive health, logistic regression, effect modification, sub-Saharan Africa, public health