Antioxidant vitamin status in the serum and amniotic fluid of women with premature rupture of the fetal membrane

The purpose of this study was to examine the status of antioxidant vitamins in women with premature rupture of the fetal membranes. Specimens of blood and amniotic fluid were obtained from 80 pregnant subjects included both smokers and non-smokers during the third trimester. The concentrations of ascorbic acid (ASA), $beta$-carotene, retinol and $alpha$-tocopherol in serum and amniotic fluid were determined. The experimental group consisted of those subjects with PROM while the control subjects were those with normal pregnancy. No statistical differences were found between the PROM and control groups in retinol and vitamin E concentrations in amniotic fluid and serum. Serum ASA concentrations of PROM subjects were not different from controls, but the PROM subjects had significantly lower amniotic fluid ASA concentrations. However, in a study with fewer subjects a lower serum ASA concentration in the PROM subjects was observed. The ratio of amniotic fluid ASA concentration to ASA serum concentration was significantly lower in PROM patients than in controls in both studies. This suggests that low levels of ASA in the amniotic fluid, but not in serum is better associated with PROM. A low amniotic fluid concentration of ASA may reflect an inefficient transfer and/or increased fetal utilization. Alterations in ASA concentration in the amniotic fluid may affect the integrity of the chorioamnion leading to PROM. $beta$-Carotene was not found in the amniotic fluid. Serum $beta$-carotene levels were significantly lower in the PROM group compared to the control group. Low concentrations of $beta$-carotene in maternal serum in smokers not only associated with poor maternal outcome (PROM) but also compromised the fetal outcome (decreased birth weight). Maintenance of adequate serum $beta$-carotene concentration and amniotic fluid ASA in smokers may result in better maternal and fetal outcome. This study demonstrated that nutrition is an important factor in the prevention of PROM.