High burden of histology-confirmed placental malaria and associated adverse birth outcomes among primigravidae in Northwestern Tanzania: a cross-sectional study

BACKGROUND: Malaria remains a major public health problem in Sub-Saharan Africa, including Tanzania, contributing significantly to maternal and neonatal morbidity and mortality. Placental malaria [PM] is linked to adverse fetal outcomes such as preterm birth, low birth weight, small-for-gestational-age infants, congenital malaria, and intrauterine death. Primigravidae are particularly vulnerable due to limited malaria-specific immunity and socio-economic barriers. This study aimed to determine the prevalence of placental malaria, fetal outcomes, and associated factors among primigravidae women delivering at Sengerema Designated District Hospital [DDH], Mwanza, Tanzania. METHODS: A hospital-based cross-sectional study enrolled 422 primigravidae women from October 2024 to April 2025. Structured questionnaires and reviews of antenatal care [ANC] cards captured socio-demographic, obstetric, and medical information. Maternal peripheral, cord, and placental blood were screened for malaria using rapid diagnostic tests [RDT], microscopy, and placental histology. Neonatal outcomes recorded included birth weight, gestational age, survival, and growth for gestational age. RESULTS: Among 422 primigravidae, malaria prevalence was higher by microscopy than mRDT in maternal 19.7% [95% CI 15.9-23.5) and 6.9% (95% CI 4.5-9.3], respectively Histopathology showed 39.8% prevalence. Adolescents had higher infection rates. Active, active-chronic, and past chronic infections were 15.4%, 13.0%, and 11.4%, respectively. The study showed histologically confirmed PM prevalence of 39.8% [95% CI 35.1-44.5], and 23.7% [95% CI 19.6-27.8] by microscopy. The prevalence of maternal peripheral malaria and congenital malaria by microscopy was found to be 19.7% [95% CI 15.9-23.5 and 6.9% (95% CI 4.5-9.3], respectively. Significant predictors of PM included fewer than four ANC visits [AOR = 1.75, p = 0.04] and moderate anemia [AOR = 1.84, p = 0.04]. PM was significantly associated with low birth weight [p = 0.01], preterm birth (p = 0.001), and small-for-gestational-age neonates [p = 0.048]. CONCLUSION: Placental malaria is highly prevalent among primigravidae women attending Sengerema DDH. Early ANC attendance, supervised uptake of IPTp, and improved diagnostic detection are critical to reducing malaria-related maternal and neonatal complications. LIMITATION: Cross-sectional design limits causality and generalizability. Use of LNMP and lack of PCR may have caused misclassification and under-detection. Exclusion of HIV-positive women and incomplete ITN/IPTp assessment may affect applicability.