Serum ferritin: a predictor of early spontaneous preterm delivery

To identify biochemical indices for iron and protein nutriture as well as acute-phase reactants as predictors of preterm delivery.

In this nested case-control study, serum samples were obtained at about 24 weeks' gestation from 94 indigent multiparas. These cases were defined based on having a spontaneous delivery of 32 weeks or less (n = 31) with two control groups, one delivering spontaneously at 33-36 weeks (n = 32) and the other delivering spontaneously at 37 weeks or more (n = 31). The concentrations of iron, ferritin, transferrin, transferrin saturation, and transferrin receptor were measured as indices of iron status. The concentrations of acute-phase reactants, including C-reactive protein, alpha-2-macroglobulin, beta-2-microglobulin and ceruloplasmin, were also measured, along with albumin, prealbumin, retinol-binding protein, copper, and zinc.

Serum ferritin concentrations were negatively correlated with gestational age at birth (P = .034). For subjects having serum ferritin levels above the median compared with those below, the odds ratio of having an early spontaneous preterm delivery was 2.99 (95% confidence interval 1.13-7.89). The other indices, including iron status and the acute-phase reactants, were not significantly associated with gestational age at birth.

Elevated serum ferritin levels during the second trimester are predictive of early spontaneous preterm delivery, possibly because these reflect an acute-phase reaction to subclinical infections that are closely associated with premature delivery.