Negative group B streptococcus is normal. The presence of group B streptococcus in the vagina and rectum is not pathogenic in normal healthy people, but if a pregnant woman has this bacterial infection, it can cause a variety of diseases. Such as puerperal infection in pregnant women, combined with bacteremia, urinary tract infection, etc. It can also easily lead to amniotic cavity infection, premature rupture of fetal membranes, and can also induce preterm delivery. During delivery, the newborn is prone to infections such as neonatal sepsis, pneumonia, meningitis, etc. when exposed to amniotic fluid and birth canal. Cesarean delivery also cannot prevent neonatal infection, so it is now recommended that pregnant women at 35-37 weeks of gestation be routinely tested for group B streptococci and need prompt treatment if they test positive.