Outbreak of Human Metapneumovirus Infection in Children in Chongqing, China

tested positive for adenovirus. RESULTS: Between January 2005 and December 2006, 193 placenta samples (71 from preterm deliveries and 122 from term deliveries) were collected in Alexandra’s Maternity Hospital in Athens, Greece. The adenoviral genome was isolated in 54 (28%) of 193 placentas. The frequency of adenovirus detection in preterm placentas compared with those from term placentas was significantly increased (29 of 71[41%] vs 25 of 122 [20%]; P .002; odds ratio [OR]: 2.6 [95% confidence interval (CI): 1.4–5.1]). Stratification by gestational age (GA) revealed a stronger association between preterm delivery and adenovirus detection as GA decreased below 33 weeks (GA 29 weeks, OR: 2.8 [95% CI: 1.1–7.0]; and GA 30–33 weeks, OR: 2.7 [95% CI: 1.1–6.5]). In the subgroup of deliveries at 34 to 36 weeks’ GA, the association was no longer significant (OR: 2.6 [95% CI: 0.9–7.0]). Adenoviral genome detection followed the seasonal variation of adenovirus respiratory infections (beginning of March to end of June). Chorioamnionitis was present more frequently in the adenovirus-positive preterm placentas compared with term placentas (P .006). The presence of villitis (P .03) and chorioamnionitis (P .02) was significantly increased in the adenovirus-positive preterm placentas compared with preterm adenovirus-negative placentas. CONCLUSIONS: Our results indicate that there is an association between placental adenoviral genome detection and spontaneous early premature birth. Adenovirus may cause preterm birth through placental inflammation (chorioamnionitis and villitis).