Elevated amniotic fluid ferritin levels are associated with inflammation-related pregnancy loss following mid-trimester amniocentesis

Abstract

Objective: Occult infection accounts for up to 12% of pregnancy losses following genetic amniocentesis. Elevated serum and cervical fluid levels of ferritin, an acute-phase reactant, have been associatedwith spontaneous preterm delivery. We determined the association between amniotic fluid (AF) ferritin levels and post-amniocentesis pregnancy loss.Methods: We performed a case-control studyinvolving 66 women with a non-anomalous fetus who had a spontaneous pregnancy loss within 30 days following genetic amniocentesis and 66 term controls matched for maternal age, gestational age, time oftest and indication for amniocentesis. Amniotic fluid ferritin and interleukin-6 (IL-6) levels were measured using commercially available kits.Results: Mean (± SD) AF ferritin levelswere similar between the cases (19.3 ± 21.4 ng/ml) and the controls (19.8 ± 22.7 ng/ml) (p = 0.9). Mean (± SD) AF IL-6 levels were significantly higher in the women with post-amniocentesispregnancy loss (4.0 ± 13.1 ng/ml) than in controls (0.5 ± 0.7 ng/ml) (p = 0.04). A significant proportion (12.1%, 8/66) of the women with postamniocentesis pregnancy loss had elevatedamniotic fluid IL-6 levels (> 3 SD, 2.5 ng/ml) indicating inflammation, as compared to none in the control group (p = 0.01). In this subgroup of women with pregnancy loss and elevated IL-6 levels,AF ferritin levels were significantly elevated (52.0 ± 45.5 ng/ml) compared to the level in women who had a term delivery (19.8 ± 22.7 ng/ml) (p = 0.002), and were strongly correlatedwith IL-6 levels among the cases (r = 0.67, p < 0.001).Conclusion: The strong correlation of AF ferritin with IL-6 levels, along with the high ferritin values in cases withhigh AF IL-6, indicates that ferritin is a marker of inflammation in asymptomatic women destined to have an early pregnancy loss.