ObjectiveWe aimed to evaluate the relation between plasma ascorbic acid levels and the occurrence of preterm premature rupture of membranes (PPROM) and whether patients with ascorbic acid deficiency have predisposition to microbial invasion, as revealed by serum interleukin-6 (IL-6) levels and confirmed by placental culture sensitivity evaluation.MethodsThis controlled study involved 50 women with PPROM at gestational age between 28 and 36.6 weeks. Fifty patients with uncomplicated pregnancy and intact membranes were observed as control group. Serum ascorbic acid and IL-6 levels were evaluated for PPROM group subjects and controls, matched by their gestational age and body mass index. Repeat samples for IL-6 were taken after 48 hours of admission in PROM group subjects and at the onset of labor in controls. Placental membranes were sent for culture sensitivity evaluation after delivery.ResultsThe mean plasma level of ascorbic acid was 0.60±0.35 mg/dL and 1.18±0.43 mg/dL in the PPROM and control groups, respectively, showing significant difference. Plasma IL-6 level rose from 18.18±5.94 pg/mL to 34.32±7.31 pg/mL after 48 hours of admission in the PPROM group (P=0.000). Plasma IL-6 level in controls rose from 5.59±4.36 pg/mL at admission to 7.36±3.67 pg/mL at the onset of labor. Membrane culture test results were positive in a total of 40 samples, of which 37 samples were from the PPROM group subjects.ConclusionVitamin C deficiency, when complemented with elevated serum IL-6 level, can predict susceptibility to PPROM in the third trimester; the risk increases in women with prior history of similar pathology.