The results of the current study indicated disproportionate concentration of IPTp-SP intake was pro-rich. Four or more antenatal visit and education status were significantly associated with IPTp utilization in the adjusted odds ratio. This study shows that the pregnant women who took at least one or more doses of IPTp were 63.6%. Among IPTp users, 35.1% took one dose, 38.6% took two doses and 26.2 took three doses and more. As recommended by WHO, pregnant women should receive at least 3 doses of Sulphadoxine pyrimethamine, which was revised to a monthly administration during pregnancy (19), necessitating the need to increase its access. Recent studies in Ghana and Malawi reported three or more doses to be 64.5% and 70.2%, respectively (20, 21). Although the coverage of at least one dose of IPTp use has increased from 27% in 2013 to 64% in 2018, the coverage of three or more doses is much lower than other studies (14). Even for the uptake of at least one dose of IPTp, the Nigerian Demographic & Health Survey reports variation among pregnant women in urban and rural areas (72.6 & 58.0% respectively) (14).
The value of the concentration index of IPTp intake was 0.180, indicating an increased use of IPTp among the rich. Further, decomposition of IPTp revealed that the variables wealth index and the level of education as the main contributors. On the other hand, age, marital status, place of residence, region and parity had insignificant influence to the observed socioeconomic inequality. Another study reported from earlier work in Nigeria, using only the concentration index to assess inequality, also showed the use of IPTp utilization as pro-rich (13). This finding was comparable with the study reported from Kenya (23) which shows that poor individuals were less likely to use any kind of antimalarial drugs for pregnant women. In other studies, in some developing countries, IPTp use during pregnancy was concentrated among women in the richest households (24-26).
In contrast, the study reported by Mathanga et al (12) revealed no inequality between pregnant women on IPTp utilization. The difference between our finding and previous study results is probably because antenatal attendance is very high in Malawi across the socioeconomic quintiles, providing a great opportunity to reach all pregnant women with IPTp, unlike in Nigeria where there is stock out of the drug as reported in some studies (27).
The adjusted odds ratio showed that covariates such as higher educational status and adequate antenatal visits significantly contributed to the IPTp utilization during pregnancy in Nigeria. Women with secondary and higher education had higher odds of taking IPTp-SP compared to those with no education. This reveals that educated women are aware of the effect of malaria in pregnancy, consistent with other studies that showed educated women are more likely to take IPTp-SP (28, 29). The number of ANC visits was significantly associated with at least one dose of IPTp-SP. This is not surprising because pregnant women are recommended to be given the drug during the ANC visits (4). Although findings from a systematic review shows inconsistent association between the ANC attendance and the IPTp uptake (30), the possible reason of the variation is that some women attend ANC but were not given SP due to stock out (31, 32). Due to the high correlation observed between ANC visits and IPTp in this study, the ANC variable was excluded during the decomposition analysis.
The odds of taking a dose of SP among women with high parity (three or more children) was lower in the bivariate analysis. However, the association was no longer significant after adjusting for education status, age, marital status, region, antenatal visits and wealth index. Ideally women with more children should have known the importance of IPT due to previous pregnancies. This is in consonance with a study by Bouyou-Akotet et al which shows that having more than four children lowers the intake (33). This result contradicts a study in Uganda which reported that women with more children used IPTp due to the possible exposure to the message of its significance (34). Age, marital status and place of residence were not significant in the multiple regression but age and place of residence were significant in the univariate model.
The present study has some limitations. The cross sectional nature of the study design could not show the causal relationship between the available inequality on IPTp utilization and the factors that contributed to the inequality. In addition, all potential determinant factors of inequality were not included in the analysis. This might limit the comprehensiveness of our findings on the observed inequality.