Placental isoferritin measured by a specific monoclonal antibody as a predictive marker for preterm contraction outcome.

The serum levels of placental isoferritin and normal ferritin in 25 women with preterm contractions (mean +/- SE gestational age 28.8 +/- 4.7 weeks) were compared with those in 14 control women with uncomplicated pregnancies (29.1 +/- 7.3 weeks). The serum concentration of placental isoferritin in women with preterm contractions (15.3 +/- 6.2 U/mL) was significantly lower than that in normal pregnant women (87.6 +/- 22.6 U/mL) (P = .005). The level of normal ferritin in women with preterm contractions (30.6 +/- 4.16 ng/ml) was lower than that in women with normal pregnancies (67 +/- 9.6 ng/mL) (P = .01); however, both were within the normal range. Serum placental isoferritin levels correlated with pregnancy outcome; low placental isoferritin (up to 10 U/mL) was a sensitive (71.5%) indicator of preterm labor. Low placental isoferritin had a positive predictive value of 59% and a negative predictive value of 71%. These results suggest that placental isoferritin may serve as a predictive marker for the prognosis of preterm contractions.