Inflammatory cytokines and antioxidants in midtrimester amniotic fluid: correlation with pregnancy outcome.

Abstract

Elevated interleukin-6 (IL-6) level in midtrimester amniotic fluid is associated with preterm delivery. We hypothesized that, in patients with elevated IL-6, vitamin C and alpha-fetoprotein may provide protection from spontaneous preterm delivery through antioxidant functions. Antioxidant potential of alpha-fetoprotein was assessed in vitro. Amniotic fluid was collected from a prospective cohort of patients who underwent midtrimester amniocentesis. In patients with IL-6 >600 pg/mL, alpha-fetoprotein, vitamin C, tumor necrosis factor-alpha, tumor necrosis factor receptors, and antioxidant capacity were compared between subjects with spontaneous preterm and term deliveries. Alpha-fetoprotein demonstrated 75% the antioxidant capacity of albumin in vitro. Of 388 subjects, 73 women had elevated IL-6 levels. Among these subjects, alpha-fetoprotein, but not vitamin C, was significantly lower in 9 women with preterm birth. Antioxidant capacity correlated with vitamin C and tumor necrosis factor receptors, but not with alpha-fetoprotein or pregnancy outcome. Amniotic fluid alpha-fetoprotein, but not vitamin C, may protect against preterm birth in patients with elevated midtrimester IL-6 levels.