Oxidative stress parameters as markers of the different trimesters in normal pregnancy
Pregnancy has been associated with changes in physiologic and metabolic functions accompanied by a high metabolic demand and elevated requirements for tissue oxygen with eventual increase in oxidative pressure on the antioxidant defence system of the body. Thus, it was based on this premise that some markers of pro-oxidant- antioxidant status of pregnancy compared with non-pregnant state were assessed including, marker of lipid peroxidation (malondialdehyde, MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidise (GPx). A total of 41 apparently healthy female volunteers were used for this study made up of 36 pregnant females at different trimester of pregnancy, categorised into three (3) groups of 12 each per trimester, and whose ages ranged between 19 years and 40 years. Standard biochemical assays were employed in the assessment of these markers. The level of lipid peroxidation (MDA) increased progressively for the pregnant subjects (p<0.05) at the third trimester (18.2mmole/ml) compared to the non-pregnant controls (2.3mmole/ml); an increase in SOD activity was also observed (p<0.05) at the third trimester (8.9U/ml) compared to the control (6.3U/ml) contrary to some other researches; while decrease in CAT (9.2U/ml) and GPx (7.8U/ml) activities at the third trimester compared to the non-pregnant control (p<0.05) (307.5U/ml and 9.4U/ml, respectively) were also observed. There was an observed increase in the body mass index, BMI, from first trimester, 26.4kg/m2 and second trimester, 38.4 kg/m2 to the third trimester, 42.7 kg/m2, compared to the control, 33.7 kg/m2 supporting the claims that pathologic conditions associated with pregnancy become more prominent with increase in BMI. Thus, these biochemical markers of oxidative stress, viz., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) can serve as markers to assess the stages of pregnancy and also can be used to differentiate pathologic and nonpathologic pregnant conditions.
Keywords: Antioxidants; Pregnancy; Pro-oxidants; Trimesters; Free radicals; Body mass index