Preterm labor associated with subclinical amniotic fluid infection and with bacterial vaginosis.

Maternal genital infection, particularly subclinical amniotic fluid infection, may cause preterm labor and a premature delivery. The prevalence of subclinical amniotic fluid infection was studied in 54 consecutive afebrile women in preterm labor with singleton gestations and intact fetal membranes. Microorganisms were recovered from the amniotic fluid by transabdominal amniocentesis in 13 (24%) of 54 patients. Bacteria or Candida albicans were recovered from six (11%), and genital mycoplasmas from seven (13%). Compared with women with sterile amniotic fluid, patients whose amniotic fluid contained bacteria or Candida organisms had a shorter interval from onset of preterm labor until delivery (0.6 versus 34.3 days, P less than .01), were less responsive to tocolytic therapy (0 versus 81% success rate, P less than .005), and more frequently developed subsequent intrapartum fever (83 versus 2.4%, P less than .005). In contrast, women whose amniotic fluid contained genital mycoplasmas did not differ in these parameters from those with sterile fluid. Also compared was cervical-vaginal infection among these patients in preterm labor with matched control subjects without preterm labor. In this analysis, bacterial vaginosis was identified in 43% of patients with and 14% of women without preterm labor (P = .02), yielding a relative risk of preterm labor for patients with bacterial vaginosis of 3.8. These data underscore the importance of amniotic fluid bacterial infections in preterm labor and premature delivery, and suggest that bacterial vaginosis is associated with prematurity.