Serum lipid oxidizibility in term premature rupture of the membranes

Objective: In our previous studies we have shown that the process of term labor is associated with oxidative stress, as indicated by increased susceptibility of maternal serum lipids to copper induced peroxidation. In order to continue evaluating the role of oxidative stress in the labor process, we next tested whether term premature rupture of the membranes (PROM) is also associated with increased susceptibility of maternal serum lipids to copper induced peroxidation. Design: A controlled prospective study. Setting: Tertiary care centre. Population: 31 healthy women with term PROM and 19 healthy pregnant women with intact membranes. The women were matched for maternal and gestational age. Methods: Venous blood was drawn from the women (up to 6 h after rupture of the membranes and prior to labor in the PROM group), and the kinetics of copper-induced oxidation of serum lipids ex vivo were monitored spectroscopically at 37 °C by continuous recording of absorbance at 245 nm. Results: The lag phase, reflecting resistance of serum lipids to oxidation, was similar in the PROM group when compared to the control group (43.7 ± 3.2 versus 41.9 ± 1.6 min, P = 0.61). However, the maximal rate of oxidation (V _max ) and the maximal accumulation of absorbing products (OD _max ) were shorter in the PROM group when compared to the control group (5.14 ± 0.26 versus 6.29 ± 0.40 10 ^-3 OD ₂₄₅ nm/min, P = 0.016; 0.61 ± 0.03 versus 0.71 ± 0.04 OD ₂₄₅ nm, P = 0.07). Conclusion: As opposed to term labor, term PROM is not associated with increased maternal systemic oxidative stress when compared to normal pregnant women. The role for oxidative stress in preterm PROM warrants further studies.