Dietary diversity insufficiently explains differences in prevalence of anaemia in pregnancy across regions in Nigeria: A secondary analysis of Demographic and Health Survey 2018

The prevalence of anaemia in pregnancy differs across regions worldwide. Previous studies have reported associations between diet and anaemia. Dietary intake may be affected by regional factors like culture, food production and availability. However, in Nigeria, the association between dietary diversity and region in the context of anaemia prevalence among pregnant women is unclear. This study compared the prevalence of anaemia in pregnancy across regions in Nigeria and determined the association between dietary diversity and anaemia across the regions. It was across-sectional study of 1,525 pregnant women aged 15-49 screened for anaemia in Nigeria's Demographic and Health Survey 2018. The primary outcome was anaemia (haemoglobin concentration < 11g/dl, irrespective of trimester). The explanatory variable was minimum dietary diversity for women (MDD-W) defined as the consumption of at least five out of ten food groups on the day preceding the interview, stratified by region. Logistic regression analyses were used to determine the association between dietary diversity and anaemia in pregnancy by region. The prevalence of anaemia in pregnancy was 61.1% and it ranged from 55.2% in South-West to 71.1% in South-East region, p = 0.038. Less than half of pregnant women met the MDD-W requirement (45.8%). There was a significant crude association between MDD-W and anaemia, OR: 0.78 (95%CI: 0.60 - 0.99), which was lost when confounders were included, aOR: 0.85 (95%CI: 0.66-1.10). Compared to North-West region, anaemia in pregnancy was significantly higher in North Central region aOR:1.90 (1.14-3.16). The model with an interaction term between MDD-W and region was not a better fit for the data (LRtest p < 0.001) in multivariable model. In conclusion, the prevalence of anaemia in pregnancy is high in Nigeria and varies across regions, not only due to dietary diversity. Region is not an effect modifier of the association between MDD-W and anaemia.