Patients with an SGA fetus were offered amniocentesis for genetic indications, to assess the microbial status of the amniotic cavity and to assess fetal lung maturity. In patients undergoing cesarean delivery, amniotic fluid was retrieved intra-operatively. Amniotic fluid was transported in a capped sterile syringe to the clinical laboratory where it was cultured for aerobic and anaerobic bacteria, including genital mycoplasmas, as described previously.[16 (link)] A white blood cell (WBC) count[64 (link)] and Gram stain[58 (link)] of amniotic fluid were also performed shortly after collection using methods previously described. Shortly after the amniocentesis, amniotic fluid not required for clinical assessment was centrifuged at 1300 × g for 10 minutes at 4°C, and the supernatant was aliquoted into gamma-irradiated nonpyrogenic DNase/RNase-free cryovials (Corning, Acton, MA, USA), and immediately frozen at −70°C. Amniotic fluid IL-6 and matrix metalloproteinase (MMP)-8 concentrations were determined using a specific and sensitive immunoassay which had been validated for amniotic fluid.[43 (link)] IL-6 and MMP-8 determinations were performed after all patients were delivered and were not used in clinical management.