At term gestation, less than 1% of women with intact membranes will have organisms cultured from amniotic fluid.6 The rate can be higher if the integrity of the amniotic cavity is compromised by procedures before birth (eg, placement of a cerclage or amniocentesis).6 In women with preterm labor and intact membranes, the rate of microbial invasion of the amniotic cavity is 32%, and if there is preterm premature rupture of membranes (PPROM), the rate may be as high as
75%.7 Many of the pathogens recovered from amniotic fluid in women with preterm labor or PPROM (eg, Ureaplasma species or Mycoplasma species) do not cause early-onset sepsis.8–10 However,
both Ureaplasma and Mycoplasma organisms can be recovered from the bloodstream of infants whose
birth weight is less than 1500 g.11 When a pathogen (eg, GBS) is recovered from
amniotic fluid, the attack rate of neonatal sepsis can be as high as 20%.12 Infants born to women with PPROM who are colonized with GBS have an estimated attack rate of 33% to 50%
when intrapartum prophylaxis is not given