The Research Of The Relationship Between Chorioamnionitis And Preterm Labor

ObjectiveThe purpose of this research was to draw up the relation between chorioamnionitis and preterm labor and its effects on preterm infants.The histological features of placenta and fetal membranes in subgroups of preterm delivery were observed.Polymerase chain reaction(PCR) was used to detect the presence of microbial 16s rRNA and ureaplasma urealyticum(UU) in placenta,fetal membranes,and,wherever possible,respectively.We aimed to explore the effects of antenatal infection on fetus and their relationship with the outcome of premature infants.Methods30 preterm birth between November 2007 and March 2008 in maternity department of our hospital were collected,including 16 cases with preterm prelabor rupture of membranes(PPROM)(rupture time＞18h),8 cases with pregnancy hypertension and 6 cases spontaneous preterm labor.18 of them were in preterm deliveries of＜32 wk gestation,the others(12) in＞32 wk gestation.10 were full-term delivery.Fetal membranes and placentas were obtained.Amniotic fluid,cord blood serum,blood from all babies and gastric fluid(by feeding tubes,half an hour after birth),tracheal secretions from infants needing mechanical ventilation,and,wherever possible,were collected, respectively.The parts of placenta and fetal membranes were in 10%formalin-fixed, paraffin-embedded.All the specimens were stored under -70℃,except for parts of placenta and fetal membranes as histological observation.According to the diagnostic criteria of chorioamnionitis,the histopathological features of placenta and fetal membranes were observed under microscope.PCR was used to detect the presence of microbial 16s rRNA and UU in placenta,fetal membranes,and,wherever possible,respectively.The results were expressed in measurement data.Statistical software SPSS13.0 was applicated, X~2 test used to compare the rate,p values of＜0.05 were considered statistically significante.Results1.The pathology of fetal membranes and placentasAccording to the pathological diagnostic criteria of corioamnionitis,21 cases were diagnoses as chorioamnionitis.It showed that neutrophil and lymphocyte infiltrated, especially in fetal membranes.Out of 21 with chorioamnionitis,14 were PPROM,which was significantly higher than the other preterm groups and full-term group,p＜0.05. Chorioamnionitis were mainly in less than 32 weeks gestational age or babies whose birth weight was less than 1500 grams,with no significant relationship between gender and delivery mode.2.The results of 16SrRNA and ureaplasma urealyticum geneFrom all deliveries,12 were 16SrRNA gene-positive,10 were UU-positive and eight cases were both positive.All of them were premature birth.9(9/16,56%) cases were 16SrRNA-positive and 8(8/16,50%) cases UU positive in PPROM group,which was significantly higher than other groups,p＜0.05.10 cases with 16SrRNA-positive were diagnosed as chorioamnionitis.3.The positive rate of 16SrRNA and ureaplasma urealyticum genes in all specimensThe positive rate of 16SrRNA and ureaplasma urealyticum gene in fetal membranes and placentas were higher than other samples.4.The relationship between delivery mode and intrauterine infectionOur results showed that there was no significant relationship between cesarean section and vaginal delivery of the presence of 16SrRNA and ureaplasma urealyticum in placenta and fetal membrane,p＞0.05.5.The effects of chorioamnionitis on premature infants.In all 30 premature infants,9 suffered from RDS right after birth who needed mechanical ventilation.Whereas 18 developed different presentation in the first 3 days of life.The signs were subtle that present apnea,feeding intolerance,dark skin color patterns, hypothermia,abdominal distension,respiratory distress and so on.12 of 18 were PPROM, 10 of 12 with PPROM were diagnosed as chorioamnionitis.The incidence of infection in PPROM group was significantly higher than other groups.The positive 16SrRNA and UU in infected infants was 50%(9/18) and 38.9%(7/18),respectively.Conclusion1.Chorioamnionitis is one of the most reasons in premature rupture of membranes and preterm labor.2.Chorioamnionitis and the detection of microbial gene will be significantly important in clarifying intrauterine infection.They both can determine the outcome of preterm infants.