The oxidative stress index increases among patients with hyperemesis gravidarum but not in normal pregnancies

Objective: The etiology and pathogenesis of hyperemesis gravidarum (HG) is still undetermined and has been suggested to involve oxidative stress. We aimed to evaluate the status of oxidative stress in HG by measuring the levels of total oxidant status (TOS), total antioxidant status (TAS), and by calculating the oxidative stress index (OSI). Methods: In a case-control trial, fasting morning blood samples of patients with HG (n = 41) and healthy pregnant women (n = 39) were collected for analysis of serum TOS and TAS values as well as for calculation of OSI according to the formula: OSI = TOS / TAS x 100. Results: Serum TOS and TAS levels were similar in both groups. However, serum TAS levels were lower among HG patients compared to controls, which resulted in an increase in OSI (P = 0.025). Discussion: The present study supports the role of systemic oxidative stress, reflected by an imbalance between the TOS and TAS, in patients with HG. Our findings distinguish the mechanism underlying oxidative stress to result from reduction of antioxidants rather than an increase in oxidants.