Decomposition of socioeconomic inequalities in the uptake of intermittent preventive treatment of malaria in pregnancy in Nigeria: evidence from Demographic Health Survey

Background: Although malaria in pregnancy is preventable with the use of intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP), it still causes maternal morbidity and mortality, in sub-Saharan Africa and Nigeria in particular. Socioeconomic inequality leads to limited uptake of IPTp-SP by pregnant women and is, therefore, a public health challenge in Nigeria. This study aimed to measure and identify factors explaining socioeconomic inequality in the uptake of IPTp-SP in Nigeria. Methods: The study re-analysed dataset of 12,294 women aged 15-49 years from 2018 Nigeria Demographic Health Survey (DHS). The normalized concentration index (Cn) and concentration curve were used to quantify and graphically present socioeconomic inequalities in the uptake of IPTp-SP among pregnant women in Nigeria. The Cn was decomposed to identify key factors contributing to the observed socioeconomic inequality in the uptake of adequate (≥3) IPTp-SP. Results: The study showed a higher concentration of the adequate uptake of IPTp-SP among socioeconomically advantaged women (Cn = 0.062; 95% confidence interval [CI] = 0.048 to 0.076) in Nigeria. There is a pro-rich inequality in the uptake of IPTp-SP in urban areas (Cn = 0.283; 95%CI = 0.279 to 0.288). In contrast, a pro-poor inequality in the uptake of IPTp-SP was observed in rural areas (Cn = -0.238; 95%CI = -0.242 to -0.235). The result of the decomposition analysis indicated that geographic zone of residence and antenatal visits were the two main drivers for the concentration of the uptake of IPTp-SP among wealthier pregnant women in Nigeria. Conclusion: The pro-rich inequalities in the uptake of IPTp-SP among pregnant women in Nigeria, particularly in urban areas, warrant further attention. Strategies to improve the uptake of IPTp-SP among women residing in socioeconomically disadvantaged geographic zones (North-East and North-West) and improving antenatal visits among the poor women may reduce pro-rich inequality in the uptake of IPTp-SP among pregnant women in Nigeria