Group B streptococcal colonization in pregnancy.

Group B beta hemolytic streptococcal infection of the newborn, acquired from the maternal genital tract, has emerged as an important cause of morbidity and mortality. In that the risk to the infant for colonization and infection may relate to the degree of streptococcal exposure, a semiquantitative determination of genital tract colonization was made in 210 pregnant women. Twelve women (6%) were colonized with 10(0) to 10(5) colonies of streptococci per sample. Among colonized women, 70% had used oral contraceptives in the year prior to pregnancy, whereas only 35% of uncolonized women gave such a history (P less than .05). There was an inverse relation between colony count and duration of pregnancy. Six of 9 untreated, colonized women had 1 to 3 repeat cultures which were negative for streptococci indicating that treatment for carriers, if available, would not be necessary much of the time.