Active labour is associated with increased oxidisibility of serum lipids ex vivo.

Objective: As a first step towards evaluating the role of oxidative stress in the process of labour, we tested whether term labour is associated with increased oxidisibility of maternal serum lipids.
Design: A controlled prospective study.
Setting: Tertiary care centre.
Population: Twenty healthy women in active labour and 20 healthy pregnant women not in labour (controls) matched for maternal and gestational age.
Methods: Venous blood was drawn from women in both groups. Serum levels of lipid peroxidation products and the kinetics of copper-induced oxidation ex vivo were monitored spectroscopically at 37 degrees C by continuous recording of absorbance at 245 nm.
Main Outcome Measures: Oxidative stress parameters.
Results: The initial optical density (OD) at 245 nm, attributed to preformed dienic hydroperoxides and 7-keto-cholesterol (main products of lipid peroxidation), was higher in the labouring group than in the controls (1.30 +/- 0.11 vs 1.18 +/- 0.09, OD 245 nm, respectively, P < 0.001). The lag phase, reflecting resistance of serum lipids to oxidation, was significantly shorter in the labouring group than in the controls (43.2 +/- 1.4 vs 56.2 +/- 4.7 min, respectively, P = 0.01).
Conclusion: High levels of serum hydroperoxides and decreased resistance of serum lipids to copper-induced peroxidation ex vivo suggest labour to be associated with high oxidative stress. Whether oxidative stress is involved in initiating the labour process or is consequent awaits further studies.