Reduced total antioxidant status in postterm pregnancies

The placenta is the major source of oxidative stress in normal human pregnancy. The placental tissue is typically functional in postterm pregnancies. We hypothesized that such pregnancies experience deteriorating oxidative balance and increasing oxidative stress. In this case-control study, our aim was to investigate the oxidative status in postterm pregnancies comparing with term by using total antioxidant status (TAS) measurement.

Fifty pregnant women who were in their 41st gestational week (GW) and whose labor had not yet started were selected for the study group. Fifty subjects whose spontaneous labor onset and who delivered before their 41st GW were included for control group. Venous blood samples were obtained from each participant before the onset of labor. A premixed reagent was used to obtain serum TAS measurements from the blood samples. The Mann-Whitney test was used to compare the groups.

Age, gravity, and parity of the subjects were similar between the groups (p> 0.05). Body mass index (BMI) were statistically higher in postterm group (p =0.011). The median (interquartile range) TAS level was lower in the pregnancies beyond 41 weeks than term pregnancies [1.69 (0.12) mM vs 1.75 (0.20) mM, (p< 0.05)].

A lower total antioxidant status in past days pregnancy suggests an association with decreased oxidative status compared to term. It can be speculated that pregnancies beyond 41 weeks are associated with decreased oxidative stress and this may be play a role in the etiology of the prolonged pregnancy.