Histological placental abnormalities and associated factors among malaria smear-positive women delivering at two tertiary hospitals in Uganda: a comprehensive multicenter cross-sectional study

Abstract

Malaria in pregnancy may disrupt placental structure and function, but evidence describing placental abnormalities among malaria-positive women in Uganda remains limited. This study determined the prevalence and patterns of gross and histological placental abnormalities and examined associated factors among malaria smear-positive women delivering at two Ugandan referral hospitals. A multicenter hospital-based cross-sectional study was conducted among 124 malaria smear-positive women delivering at Jinja and Hoima Regional Referral Hospitals between 1st May and 1st September 2023. Placentas underwent standardized gross examination, tissue sampling and haematoxylin-and-eosin histology. The primary outcome was the presence of any recorded histological placental abnormality. Multivariable logistic regression was used to identify independently associated factors. Histological placental abnormalities were identified in 79 of 124 placentas (63.7%; 95% CI 55.0–71.6). Placental weight below 500 g occurred in 93 (75.0%) placentas, while 98 (79.0%) had central umbilical-cord insertion and 84 (67.8%) had a diameter of 15–20 cm. Histological lesions were not mutually exclusive. Infarction was the most frequent lesion (62, 50.0%), followed by inflammation (43, 34.7%), fibrin deposition (39, 31.5%), increased syncytial knotting (38, 30.6%), thrombosis (35, 28.2%) and fibrinoid deposition (33, 26.6%). Maternal age < 20 years was associated with higher odds of histological abnormalities than age ≥ 20 years (aOR 14.54; 95% CI 3.64–58.05; p < 0.001). BMI ≥ 30 kg/m² was associated with lower odds than BMI < 25 kg/m² (aOR 0.19; 95% CI 0.04–0.83; p = 0.027). Histological placental abnormalities were common among malaria smear-positive women. Placental weight < 500 g was the predominant gross finding, while infarction was the most frequent histological lesion. Maternal age < 20 years and BMI ≥ 30 kg/m² were independently associated with the outcome. Malaria prevention and antenatal assessment should be strengthened, particularly for pregnant adolescents, alongside prospective studies with malaria-negative comparison groups.