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°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.