Background Malaria in pregnancy carries a risk of significant adverse maternal and infant outcomes. Intermittent preventive treatment in pregnancy (IPTp) is advocated to reduce its occurrence, but resistance to sulphadoxine-pyrimethamine (SP) is being reported. This study aims to describe the burden of SP resistance and determinants of its occurrence among pregnant women receiving IPTp in Nigeria.

Methods A prospective observational study is to be conducted in Ogun State over 24 months. Pregnant women 16–28 weeks gestation meeting the eligibility criteria are being enrolled; blood samples are taken for analysis pre- and post- IPTp-SP administration at scheduled intervals. Microscopy-confirmed parasitaemic samples will be analysed using PCR to detect drug resistance markers (pfdhfr and pfdhps). Participants will be followed up until 28 days post-delivery and assessed for maternal and foetal outcomes (anaemia, low birth weight, preterm delivery, placental parasitaemia, stillbirth, neonatal death). The primary endpoint is the prevalence of the SP resistance gene markers. Secondary endpoints include the prevalence of peripheral and placental parasitaemia at delivery; incidence of maternal and newborn morbidity; parasitaemia pre-IPTp and day 28 post-IPTp; risk factors for SP resistance and haemoglobin changes at delivery.

Results Following statistical analysis with STATA 14, results will be displayed in appropriate formats. Geometric mean parasite densities with 95% confidence intervals will be calculated, and proportions compared using the t-test, Chi-square or Fisher’s exact tests as appropriate. Multivariate analysis including logistic regression models will be used to test for associations between maternal characteristics and SP resistance. Level of significance will be set at p<0.05.

Conclusion In a malaria-endemic country like Nigeria with a large at-risk population, information on the effectiveness of chemoprevention is essential. Determining the proportion and extent of relevant molecular markers within the population offers an invaluable tool for epidemiological surveillance of SP resistance within this endemic setting.