While some studies have reported National prevalence rates for obesity among non-pregnant women of reproductive age group in Nigeria, this study provides new information on sub-national distribution and variation of obesity among this important population. The findings of this study will inform the interventional approach(es) to address the rising epidemic of obesity among this critical population, both nationally and sub-nationally.
This study showed that sub-national variations exist in the prevalence of obesity among non-pregnant women of reproductive age in the different states of Nigeria, even after adjusting for a wide range of commonly reported individual, household and community level predictors. Such variations have been observed in studies carried out in the United States,[15] Bangladesh,[21, 22] Cambodia,[23] China,[24] and particularly in Africa.[11, 14, 25–27] The finding of this study is important because it highlights the role of the contextual unit or the environment in which a woman lives in the prevalence of obesity. Additionally, this underscores the fact that country-wide interventions may be grossly inadequate for obesity among women of reproductive age in Nigeria.
The pattern of sub-national variation in the prevalence of obesity among Nigerian women was such that the Southern States largely had a higher burden compared to the Northern States. Similar findings of regional variations, even after controlling for risk factors, have been reported in high,[15] middle,[24] and low income countries.[14, 21, 26] A plausible argument for the regional variation in Nigeria would have been the socio-economic inequality that has been reported between the generally poorer north and richer south.[20] However, the variation still existed after adjusting for the various indicators of socio-economic status including educational status, occupational status, wealth index and residence.
Also of concern is the wide sub-national variation in the prevalence of obesity among women of reproductive age in Nigeria, with a range of nearly 50% (Sokoto – 6.9% versus Anambra – 54.6%). About half of the women in Anambra, Lagos and Rivers States were obese, with prevalence rates nearly twice the national average, while less than 10% of women in Sokoto, Yobe and Jigawa States were obese, which is less than half of the national average. Furthermore, women in Anambra and Akwa Ibom States had about 500% higher odds for obesity compared to those in Sokoto State even after adjusting for commonly reported predictors. Marked sub-national variations like this have been similarly observed in both high income and low- and middle-income countries. In United States, there were marked disparities in the obesity prevalence with some cities having 3 to 6 times higher risks of pre-pregnancy and severe obesity compared to their counterparts.[15] In another study done in China, some of the regions had more than double the odds of obesity compared to others even after controlling for common risk factors.[24] In Mali, regional variations in the obesity risk among reproductive aged women was also seen, with one region in particular (Kidal) having ten times the odds (compared to reference state) after adjusting for risk factors.[26] Generally, that about a third of women of reproductive age in Nigeria are obese should be a thing of concern, but this study further shows that there is a big sub-national context to this problem in Nigeria. There is therefore a need to investigate and identify state-level determinants of obesity among women of reproductive age in each State in Nigeria. Furthermore, this finding underscores the need for state-specific interventions to curb obesity among women of reproductive age in Nigeria.
It should be noted that obesity among women in this study had statistically significant associations with age, educational status, religion, number of living children, wealth index and spouse’s educational status, even after adjusting for possible confounders. These findings corroborate the findings of previous studies among women of reproductive age in Nigeria.[11, 16, 21, 22, 25, 26] In the present study, the associations were such that women who were older, more educated, Christians, with more children, from richer households and who had more educated spouses had higher odds of being obese. This pattern of relationship has also been previously reported by studies among women of reproductive of age within and outside Nigeria.[11, 14, 16, 27] However, the finding of this study showed that these factors alone did not explain the sub-national variation of obesity among this category of women in Nigeria. There may be need to explore other methodological approaches including qualitative studies,[28–30] mixed methods,[31] and multi-level analysis,[15, 18, 22] to explain the sub-national variation in the prevalence of obesity among non-pregnant women of reproductive age in Nigeria.
A limitation of this study is its being a cross-sectional study, which means that causality cannot be determined.