Abstract: OBJECTIVE To investigate the detection of group B Streptococcus in pregnant women in late pregnancy and the effect of group B Streptococcus infection on pregnancy outcome.METHODS A total of 500 pregnant women in late pregnancy who underwent prenatal examination in the hospital from Jun.2016 to Mar.2017 were selected as the study subjects.The perianal secretions and vaginal secretions of pregnant women were collected for detection of Group B Streptococcus.The infection of group B Streptococcus in pregnant women and the effect of group B Streptococcus on pregnancy outcome and newborn were analyzed.RESULTS The positive rate of group B Streptococcus in late pregnancy was 9.40%in the 500 pregnant women（47/500）.The incidences of intrauterine distress and intrauterine infection in pregnancy outcomes of group B Streptococcus positive pregnant women were44.68%（21/47）and 17.02%（8/47）significantly higher than those of group B Streptococcus negative pregnant women（P＜0.05）.The group B Streptococcus positive rate,and the incidences of upper respiratory tract infection and pneumonia in newborns of group B Streptococcus positive pregnant women were 23.40%（11/47）,19.15%（9/47）and 21.28%（10/47）,which were significantly higher than those of the newborns of the Group B Streptococcus negative pregnant women（P＜0.001）.CONCLUSION Group B Streptococcus infection in late pregnancy can lead to fetal distress,intrauterine infection and increased incidence of neonatal infection,affecting the outcome of pregnancy and neonatal health.Therefore,group B Streptococcus screening should be carried out during pregnancy to improve the prognosis.