FCM is an issue that has attracted the attention of the global community due to its importance in maternal health. Nigeria has been identified among the countries with a high prevalence of FCM [42]. Moreover, studies have shown that if left unabated, FCM could potentially retard the attainment of the SDGs, specifically, SDG 1 (end poverty in all its forms everywhere), 2 (ensure healthy lives and promote well-being for all at all ages), 3 (ensure inclusive and equitable quality education) and 4 (gender equality and empower all women and girls). Against this background and the imperativeness to understand the determinants of FCM in Nigeria, we investigated this phenomenon. Our findings show a high prevalence of FCM in Nigeria in 2018, with girls with parity of 1–3 children had a higher likelihood of being married before the age of 18. This is worrying because despite all concerted efforts through legislations, and policies (e.g., CRA, VAPPA) to eliminate FCM in Nigeria [13], more than half of the proportion of the women who participated in the study had been married before age 18.
Results from our study revealed that the place of residence was significantly associated with the odds of experiencing FCM. It is indicative from the study that females in rural areas have a greater likelihood of experiencing FCM. A similar finding was reported by Workineh, Kibretb and Degu [43], who found that the odds of FCM were more pervasive among rural residents than the urbanite counterparts. In the same vein, this observation is consistent with the findings from Pankhurst et al. [44] that showed that rural residents had a higher likelihood of experiencing FCM compared to their urban-dwelling counterparts. A possible explanation for this finding may be that urban residents, unlike rural residents, may be exposed to female empowerment programmes and interventions and higher education, thereby shaping their thoughts and motives towards the girl child's education rather than sending these girls into marriage.
Our study revealed that having secondary or higher education was associated with lower odds of experiencing FCM compared to those with no education. The finding is consistent with several findings from Nigeria and across the globe [3, 45,46,47,48,49,50]. For instance, Mpilambo et al. [48] found a negative, significant association between formal education and early marriage among young women in Congo. The current findings iterate that education is a protective factor for FCM. This implies that one of the most effective ways to combat FCM in Nigeria is to rejuvenate and strengthen girls' formal education. Formal education at any level has significant potential in reducing the likelihood of FCM. Moreover, Envuladu et al. [45] postulate that educated parents are more likely to delay the marriage of their young female children than those with no education. Therefore, if girl child education in Nigeria is given the maximum priority, the country will be moving towards attaining the SDGs and significantly winning the fight against FCM.
Concerning the effect of religion on the likelihood of FCM, we found that young women who practiced Islam had a higher likelihood of FCM compared to those who practiced Christianity. This is worth noting as Nigeria is a country where religion contributes significantly to the formation of values, norms and practices at both the micro (individual and family) and macro-level [46]. Our finding, thus, accords with an earlier study by Braimah [12], which posits that in Nigeria, particularly in Northern Nigeria, where Islam is predominant, there is a high prevalence of female child marriages. The author continues by stating that the reason for the high likelihood of FCM among Muslims in Nigeria is grounded on the fact that, in the Hadiths, it is reported that the Prophet Muhammad married Aisha at the age of 9; therefore, justifying FCM in such communities [12].
Our study further revealed that the girls from the Yoruba ethnic group were less likely to marry before age 18 compared to the girls who belonged to the Hausa ethnic group. This corroborates an earlier study by Adebowale [13] that has also found people from the Yoruba ethnic group to be less likely to marry before age 18. A plausible explanation for this outcome could be attributed to the location of the Yoruba ethnic group. Predominantly, the Yoruba are found in the South-West of Nigeria, where most of them profess Christianity and have higher education levels compared to their counterparts from the Hausa ethnic group who are predominantly Muslim low or no formal education [13, 51].
At the community level, our findings indicate that compared to young women within the poorer wealth index, those in the richer wealth index had a lower likelihood of FCM. The result aligns with previous studies, such as Pankhurst et al. [44], who reported that poverty was a significant determinant of FCM as it increased the probability of experiencing child marriage. A similar finding was reported by Rumble et al. [3], where wealth was inversely associated with child marriage odds. Again, the result is substantiated by Corno and Voena [52], who posit that individuals from poor households find it difficult to secure credit facilities/market and, therefore, depend heavily on bride price for daily living. This may prompt parents of girls within the poorer wealth index to marry off their girl child in an attempt to reduce the financial burden associated with the upbringing of the child. Thus, corroborating the postulate that poverty is a critical driver of FCM.
Our study indicates that young women residing in the North East and North West of Nigeria had a significantly higher likelihood of marrying before age 18 compared to young women in the North Central region of Nigeria. This finding is consistent with Mobolaji, Fatusi and Adedini [46] that found Northern Nigeria to be associated with a higher likelihood of FCM. Likewise, the finding is supported by Grijns and Horii [53], who found that holding on to conservative Islamic perspectives increases a girl’s odds of marrying before age 18. This is grounded on the premise that the Hausa-Fulanis reside in Northern Nigeria and are predominantly Muslims and are influenced by Muhammad’s marriage to Aisha when she was just a child [12]. This finding also emphasizes the entrenching gender inequality and deep-rooted patriarchal systems that facilitate and spearhead FCM in these regions [54]. Beyond these justifications, Braimah [12] indicates that FCM is perceived as a conduit for preserving community virtues concerning the female child in Northern Nigeria. Thus, FCM is practiced in this region to promote chastity, cherish virginity, and prevent birth out of wedlock.
We found that young women residing in communities with high literacy levels were less likely to marry before age 18. Female child marriage is not just a social issue but an issue; it is also a serious cultural issue. As such, it is reinforced by long-standing socio-cultural norms, values, and beliefs. Through the enhancement of community literacy, certain misconceptions and myths concerning FCM. Hence, exacerbating the likelihood of young women being married before age 18. This is congruent to earlier findings that improving community literacy empowers individuals in the community and significantly facilitates the changing of retrogressive and regressive norms that fuel FCM [53].
Overall, findings from our study showed the importance of household/community level factors in FCM. This was evident from the 28% variations PSUs attributed to the household/community level predictors of FCM, which was higher than the 20% variations in PSUs attributed to the individual level predictors of FCM and the 16% attributed to all the factors. The household/community level factors also explained the greatest percentage of ICC of 8% compared to the individual level factors and all the factors together. This indicates that household/community factors are the major factors associated with FCM. Similar findings have been obtained in previous studies on the same subject [55,56,57].
Strengths and limitations
While this study used a nationally representative dataset from NDHS, which grants it the statistical power to make a generalisation of Nigeria, the study was limited in some capacities. The use of secondary data restricts the analytical possibilities and thereby limits the analysis to the association. In effect, causal inferences cannot be made from this study. Moreover, the data used was self-reported data, which is prone to some biases; however, it was outside the team's powers to validate the dataset's responses. Also, the use of secondary data, which was quantitative, does not provide a holistic comprehension of the predictors of female child marriages in Nigeria. We were unable to analyse the effect of cultural norms and beliefs on FCM since we used a secondary dataset that did not cover such issues. Another limitation of our study is that apart from ever circumcised, the rest of the independent variables measured the current status of young women while the outcome variable (age at first marriage) may have occurred in the past for some of the respondents. Hence, there is the likelihood of reverse causality between the associated factors and the outcome variables. Therefore, interpretation of the findings needs to be done, taking into consideration this key limitation.
Policy implication
The findings of this study have serious implications for policy and practice. Regarding policy, the findings that show the significant association between education and FCM bring to the fore the expedient need for the Federal Republic of Nigeria to review its educational policies to emphasize more on free and compulsory girl-child education at all levels. By doing so, the girls will be empowered to say no to FCM. More interventions should be titled to decrease the financial burden associated with educating the girl child. Moreover, we believe that the government, non-governmental organisations (NGOs) and community support officers (CSOs) must work collaboratively to significantly reduce unemployment and poverty in Nigeria. This will help parents have enough money to cater to their family rather than rely on their girl-child to marry to bring home some money. In the same vein, policies that will categorically discourage girl-child marriage about Nigerians practicing Islam should be considered with much support and emancipation by the religious leaders.
Recommendations and research implication
We recommend that future studies explore a mixed-method approach where qualitative data will be collected and analysed to provide in-depth interpretations and understanding of the determinants of FCM in Nigeria, particularly why women in Northern Nigeria are more likely to marry before age 18. Also, future studies should consider ethnographic, contextual, and ecosystem-based research.