Background Malaria infection during pregnancy can cause significant morbidity and mortality to a pregnant woman, her fetus and newborn. In areas of high endemic transmission, gravidity is an important risk factor for infection, but there is a complex relationship with other exposure-related factors, and use of protective measures. This study investigated the association between gravidity and placental malaria (PM), among pregnant women aged 14–49 in Kintampo, a high transmission area of Ghana. Methods Between 2008 and 2011, as part of a study investigating the association between PM and malaria in infancy, pregnant women attending antenatal care (ANC) clinics in the study area were enrolled and followed up until delivery. The outcome of PM was assessed at delivery by placental histopathology. Multivariable logistic regression analyses were used to investigate the association between gravidity and PM, identify other key risk factors, and control for potential confounders. Pre-specified effect modifiers including area of residence, socio-economic score (SES), ITN use and IPTp-SP use were explored. Results The prevalence of PM was 65.9% in primigravidae, and 26.5% in multigravidae. After adjusting for age, SES and relationship status, primigravidae were shown to have over three times the odds of PM compared to multigravidae, defined as women with 2 or more previous pregnancies [adjusted OR = 3.36 (95% CI 2.39–4.71), N = 1808, P < 0.001]. The association appeared stronger in rural areas [OR for PG vs. MG was 3.79 (95% CI 3.61–5.51) in rural areas; 2.09 (95% CI 1.17–3.71) in urban areas; P for interaction = 0.07], and among women with lower socio-economic scores [OR for PG vs. MG was 4.73 (95% CI 3.08–7.25) amongst women with lower SES; OR = 2.14 (95% CI 1.38–3.35) among women with higher SES; P for interaction = 0.008]. There was also evidence of lower risk among primigravidae with better use of the current preventive measures IPTp and LLIN. Conclusions The burden of PM is most heavily focused on primigravidae of low SES living in rural areas of high transmission. Programmes should prioritize primigravidae and young women of child-bearing age for interventions such as LLIN distribution, educational initiatives and treatment to reduce the burden of malaria in first pregnancy.

Background Malaria infection during pregnancy can cause significant morbidity and mortality to a pregnant woman, her foetus and newborn. In areas of high endemic transmission, gravidity is an important risk factor for infection, but there is a complex relationship with other exposure-related factors, and use of protective measures. This study investigated the association between gravidity and placental malaria (PM), among pregnant women aged 14-49 in Kintampo, a high transmission area of Ghana. Methods Between 2008-2011, as part of a study investigating the association between PM and malaria in infancy, pregnant women attending antenatal care (ANC) clinics in the study area were enrolled and followed up until delivery. The outcome of PM was assessed at delivery by placental histopathology. Multivariable logistic regression analyses were used to investigate the association between gravidity and PM, identify other key risk factors, and control for potential confounders. Pre-specified effect modifiers including area of residence, socio-economic score (SES), ITN use and IPTp-SP use were explored. Results The prevalence of PM was 65.9% in primigravidae, and 26.5% in multigravidae. After adjusting for age, SES and relationship status, primigravidae were shown to have over three times the odds of PM compared to multigravidae, defined as women with 2 or more previous pregnancies (adjusted OR=3.36 (95% CI 2.39-4.71), N=1808, P<0.001). The association appeared stronger in rural areas (OR for PG vs. MG was 3.79 (95% CI: 3.61-5.51) in rural areas; 2.09 (95% CI: 1.17- 3.71) in urban areas; P for interaction =0.07), and among women with lower socio-economic scores (OR for PG vs. MG was 4.73 (95% CI 3.08-7.25) amongst women with lower SES; OR=2.14 (95% CI 1.38-3.35) among women with higher SES; P for interaction =0.008. There was also evidence of lower risk among primigravidae with better use of the current preventive measures IPTp and LLIN. Conclusions The burden of PM is most heavily focused on primigravidae of low SES living in rural areas of high transmission. Programmes should prioritize primigravidae and young women of child-bearing age for interventions such as LLIN distribution, educational initiatives and treatment to reduce the burden of malaria in first pregnancy.

Background Although infants are vulnerable to malaria, the characteristics of their patterns of infections are not well described. This study aimed to examine the longitudinal profiles of asymptomatic infections and symptomatic malaria in the first year of life. Methods A birth cohort in Kintampo, Ghana (N = 1855) was followed actively with monthly blood sampling and passively for any febrile illness between 2008 and 2011. Malaria parasites were detected by light microscopy and infants who were infected or uninfected were identified. Infections were classified as either symptomatic or asymptomatic using fever and temperature readings over twelve months of follow up. The longitudinal infection profiles in all infants were then compared. Results: Asymptomatic infections and symptomatic malaria were observed at all ages but were rare the first months of life and the proportion of symptomatic malaria increased after six months. Among 1264 infants having microscopy data for at least eight monthly visits, four patterns were observed: parasite negative at all visits (36%), always asymptomatic (7%), always symptomatic (35%) and alternating between asymptomatic infections and symptomatic malaria (22%). The cumulative incidence of infection was highest in the alternating group, and many different profiles (87 different combinations) of asymptomatic infections and symptomatic malaria were observed in this group . Parasite densities were significantly low for the always asymptomatic group and highest for always symptomatic group. Conclusion Infants in malaria endemic areas experience highly different infection profiles over the first year of life despite living in the same area. In-depth investigations of why some infants are parasite free and others have repeated symptomatic malaria or maintain asymptomatic infections or alternate between asymptomatic infections and symptomatic malaria can contribute to understanding malaria susceptibility during infancy.