Abstract: OBJECTIVE To study the clinical effect of perinatal pregnant women infected group B Streptococcus on maternal and infant prognosis,so as to guide the clinical treatment,improved the health level of the newborn and reduced the complications of the third trimester of pregnancy.METHODS A total of 1670 cases of vaginal secretions and neonatal umbilical cord blood after birth were collected from Oct.2014 to Sep.2015 from 35 37 weeks of pregnancy of department of obstetrics and gynecology.Group B Streptococcus selective chromogenic medium（liquid）culture was used to analyze perinatal women′s group B Streptococcus infection status and the influence on pregnancy outcomes,and drug resistance situation was analyzed by the drug sensitive test method（K-B）analysis.RESULTS Totally 101 strains of group B Streptococcus were detected from 1670 cases of perinatal pregnant women specimens,with the positive rate of 6.05%.There were no penicillin,ceftriaxone and vancomycin resistant strains.The drug resistant rate to levofloxacin was 20.79%,and to erythromycin and clindamycin were relatively high of 69.31% and 51.49%.The multi-factor analysis results showed that the BMI≥28kg/m2,GDM,VVC and anemia were independent risk factors for GBS infection in pregnant women（P＜0.05）.GBS positive women had high incidence rates of premature birth and premature rupture of membranes.The neonatal pneumonia and neonatal upper respiratory tract infection of GBS positive women were significantly higher than those of GBS negative pregnant women（P＜0.05）.CONCLUSION Perinatal women carrying group B Streptococcus can increase the premature birth,abortion,puerperal infection and the incidence of fetal distress and neonatal infections,having adverse effects on the pregnancy outcome.Pathogens with clinical positive response should be conducted of drug sensitive test for effective intervention therapy,so as to guarantee the perinatal health.