Although antenatal infection is thought to play an important role in the pathogenesis of preterm labor and neonatal diseases, the exact mechanisms are largely unknown. We sought to clarify the relationship between antenatal infection and intrauterine and neonatal inflammation. Samples were obtained from 41 preterm infants of Ͻ33 wk gestation delivered to 36 mothers and analyzed for the presence of 16s ribosomal RNA (16s rRNA) genes using PCR and for the proinflammatory cytokines IL-6 and IL-8. In 16 (44%) mother-baby pairings, at least one sample was found to be positive for the presence of 16s rRNA genes. All but one of the positive samples were from mothers presenting with preterm prelabor rupture of membranes (pPROM) or in spontaneous idiopathic preterm labor. A strong association was found between the presence of 16s rRNA genes and chorioamnionitis and with funisitis. A marked increase in IL-6 and IL-8 was noted in all tissues positive for 16s rRNA genes, including placenta, fetal membranes, cord blood serum, and, where samples were available, in bronchoalveolar lavage fluid (BAL) and in amniotic fluid. Interestingly, gastric fluid was always positive for 16s rRNA genes if any other intrauterine or BAL sample was positive, suggesting that this sample may provide an alternative to amniotic fluid to identify antenatal infection. In conclusion, we have found that microbial genes are particularly prevalent in pPROM and spontaneous preterm labor groups and that their presence is strongly associated with a marked intrauterine inflammatory response. (Pediatr Res 57: 570-577, 2005) Abbreviations BAL, bronchoalveolar lavage CLD, chronic lung disease pPROM, preterm prelabor rupture of membranes rRNA, ribosomal RNA Preterm birth is the most common cause of neonatal death (1) and is associated with increased neonatal morbidity and childhood disability (2,3). Evidence from studies over the past two decades suggests that subclinical infection and inflammation of the amnion/chorion/decidua is implicated in the pathogenesis of pPROM and "spontaneous" preterm labor (4,5). More recently, intrauterine infection/inflammation has been associated with neonatal morbidity, including white matter cerebral lesions (6 -8) and CLD (9 -11). It has been estimated that as many as 40% of spontaneous preterm births may be attributed to antenatal infection (12). Furthermore, because many infections are subclinical and the women have often been treated with antibiotics, culture results may underestimate the "true" infection rates.Many studies have used amniotic fluid to identify antenatal intrauterine infection. The organisms commonly identified are vaginal commensals, suggesting ascending infection as a route of entry to the uterine cavity (13). Few studies have investigated other components of the uterine cavity to accurately identify the presence of infection and the nature of the relationship between such infection and inflammation. A clear association has been demonstrated between chorioamnionitis and intrauterine infection (14 -16). Oft...

Background: Relatively little is known about the effects of mode of delivery on long-term

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