The aim of the study is to determine if N-acetylcysteine (a potent free radical scavenger) prevents the occurrence of adverse neonatal outcomes in preterm deliveries complicated by infection associated with preterm labor or preterm premature rupture of membranes (PPROM). The working hypothesis is that in pregnancies complicated by intra-amniotic infection or inflammation, N-acetylcysteine protects the fetus by preventing the development, or decreasing the intensity and/or progression of the fetal inflammatory syndrome.