Persistent Spatial Inequalities in Contraceptive Use in Nigeria: A Bayesian Spatio- Temporal model Evidence from Demographic Health Survey Data from 2003 to 2024

In the vast landscape of public health, few tools are as quietly transformative as family planning. By allowing women to decide when and how many children to have, contraception acts as a foundation for healthier families and stronger communities. It prevents unintended pregnancies, spaces births to protect maternal health, and empowers women to pursue education and economic opportunities. Yet, the ability to access these life-changing methods is not distributed equally. In many parts of the world, geography and wealth create deep divides, where a woman's chance of using contraception depends more on her address or her bank account than on her personal needs. Understanding these patterns is crucial because national averages often hide the reality on the ground, masking pockets of progress alongside areas of stagnation. To see the true picture, researchers must look beyond simple counts and examine how these trends shift across space and time, revealing the hidden contours of inequality that shape reproductive health.

A team of researchers from the University of Abuja has undertaken a massive effort to map these hidden contours in Nigeria, the most populous nation in Africa. By weaving together data from five separate national surveys conducted between 2003 and 2024, they analyzed the lives of nearly 128,000 women aged 15 to 49. Their goal was to move past the limitations of traditional statistics, which often treat each region as an isolated island, and instead use a sophisticated modeling approach that recognizes how neighboring areas influence one another. This method allowed them to trace the evolution of contraceptive use across the country's 36 states and the federal capital territory over two decades, creating a dynamic portrait of where progress has been made and where deep disparities remain.

The results paint a story of slow, steady improvement shadowed by persistent inequality. Over the twenty-year period, the overall rate of contraceptive use in Nigeria rose from 14.5 percent to 20.7 percent. While this upward trend is encouraging, the researchers found that the gains are far from uniform. The data reveals a stark divide between the south and the north of the country. In the southern regions, particularly the southwest, contraceptive use is significantly higher, with some states showing rates well above the national average. In contrast, the northern states consistently record the lowest usage, with some areas struggling to reach even single-digit percentages. This north-south gap is not a fleeting anomaly but a deeply entrenched pattern that has held firm despite years of health interventions.

The study also illuminated how personal circumstances dictate access to family planning. Education emerged as a powerful driver; women with higher levels of schooling were more than four times as likely to use contraception compared to those with no formal education. Similarly, wealth played a decisive role, with women from the richest households nearly three times more likely to use these methods than those from the poorest families. Where a woman lives matters just as much, as urban residents enjoy significantly higher usage rates than their rural counterparts, who often face barriers like distance to clinics and a lack of available services. Marital status also influenced the numbers, with married women and those living with partners showing higher usage, while widowed or divorced women were less likely to use contraception.

What makes this research particularly valuable is how it visualizes these trends using a technique that smooths out the noise of raw data to reveal the underlying reality. The researchers found that even after accounting for education, wealth, and location, significant differences remained between states. This suggests that factors beyond individual choices—such as local cultural norms, the availability of health workers, and community attitudes—continue to shape outcomes. The maps generated by the study show that while some southern states have seen their usage rates climb steadily, many northern states have seen little change or even slight declines. The researchers calculated the likelihood of each state exceeding the national average, and the results confirm that the southern states are far more likely to be above the average, while the northern states are far more likely to be below it.

The analysis also looked at how these patterns change over time. While the country as a whole is moving in the right direction, the speed of that movement varies wildly from one state to another. Some regions have experienced rapid gains, while others have stagnated. This uneven progress indicates that a single national strategy is not enough to solve the problem. The study suggests that to truly close the gap, health interventions must be tailored to specific regions, with a particular focus on the underserved communities in the north and in rural areas. By identifying exactly where the disparities are most severe, policymakers can direct resources more effectively, ensuring that the benefits of family planning reach every woman, regardless of where she lives or how much money she has.

Ultimately, this work provides a clear, evidence-based roadmap for the future of reproductive health in Nigeria. It confirms that while the nation has made progress, the journey toward equality is far from over. The persistent spatial inequalities revealed by the study serve as a reminder that improving public health requires more than just counting users; it demands a deep understanding of the geographic and social landscapes that influence human behavior. By targeting the specific barriers faced by women in the most disadvantaged regions, Nigeria can begin to dismantle the walls of inequality that have kept millions from accessing the care they need.