Adenovirus genome in the placenta: association with histological chorioamnionitis and preterm birth

Adenovirus is isolated frequently from the amniotic fluid and has been implicated in severe neonatal infections. A case control study was carried out to examine the association of detection of adenovirus in placentas with preterm birth and histological chorioamnionitis. Placentas from preterm and full term deliveries were collected prospectively. Preterm cases were divided into three subgroups according to the gestational age. PCR was carried out on placental tissues for the detection of adenovirus genome. Placentas were evaluated histologically for the presence of chorioamnionitis. Chi-square and odds ratios (OR) were used to determine if detection of adenovirus is associated with preterm birth and histological evidence of inflammation. Seventy-one preterm and 122 full term placentas were studied. Adenovirus genome was detected in 29 (40.8%) of preterm cases and in 25 (20.5%) of the full term controls (OR = 2.6; 95% CI, 1.4-5.1; P = 0.002). Detection of adenovirus in preterm placentas was significantly higher compared to full term particularly in the lower gestational age. Detection of adenovirus in placenta followed the seasonal variation of adenovirus infections. Thirty-seven preterm and 21 full term placentas were also selected for paraffin inclusion and histological examination. Chorioamnionitis was present more frequently in preterm adenovirus-positive placentas compared to preterm adenovirus-negative placentas (75% vs. 36%; P = 0.026) as well as compared to term adenovirus-positive placentas (75% vs. 19%; P = 0.003). This study demonstrates that adenovirus infection of the placenta is associated strongly with histological chorioamnionitis and preterm birth.