Meconium-stained amniotic fluid and its association with obstetric infections

Meconium-stained amniotic fluid (MSAF) complicates the intrapartum course of 1.5% to 18% of pregnancies. In addition to predisposing to the meconium aspiration syndrome, MSAF is also an established risk factor for neonatal sepsis and for intrapartum and postpartum maternal infection. Meconium enhances the growth of bacteria in amniotic fluid by serving as a growth factor, inhibits the bacteriostatic properties of amniotic fluid, and antagonizes host defense systems such as phagocytosis, thus explaining the association between MSAF and intrauterine infection. Other evidence suggests that the presence of intraamniotic infection may actually cause passage of meconium in utero by inducing fetal enteritis and gastrointestinal hypermotility. Prophylactic intravenous ampicillin-sulbactam has been shown to be effective in significantly decreasing the rate of chorioamnionitis in patients with MSAF. Additional investigation is necessary to determine the optimal prophylactic antibiotic(s) and method of drug administration in patients with MSAF.