Placental isoferritin as a marker of early abortion in pregnancies induced by in vitro fertilization.

The relatively high rate of early pregnancy loss in artificial reproductive technology-induced conceptions has driven researchers to seek for an efficient diagnostic tool for estimating the gestational risk in these cases. Monitoring early gestation normalcy using serial beta-human chorionic gonadotrophin (beta hCG) measurements requires several days before diagnosis can be established. The objective of this study was to determine whether placental isoferritin (PLF) can be used as a predictive marker of normal pregnancy development during early stages of in vitro fertilization (IVF)-induced pregnancy. Ninety-three consecutive IVF cycles were investigated. Blood samples for PLF (enzyme linked immunosorbent assay; ELISA) and beta hCG (radio-immunoassay; RIA) determination were obtained from all women on days 11, 13 and 15 following embryo transfer. Placental isoferritin was detectable in the serum 11 days after embryo transfer in IVF conception cycles. These levels were significantly higher in normally developing pregnancies (n = 18) than in cases which eventually aborted spontaneously (n = 9) during the first trimester (mean +/- s.d.; 33 +/- 28 U/mL as compared with 1 +/- 2 U/mL; P = 0.0004; Wilcoxon test; sensitivity 94.5 per cent, specificity 88.9 per cent, positive predictive value 89.9 per cent, negative predictive value 94.5 per cent). Moreover, in those patients who later aborted, lower than normal PLF levels were detected long before the decline in beta hCG titres was evident. Considering its suppressor activity, it is expected that PLF levels would be high at the initiation of normal pregnancy. This may explain the present finding of low PLF levels in abnormally developing IVF-induced pregnancies. These preliminary data suggest that PLF can be used as a sensitive marker for detecting those cases destined to abort at a very early stage. However, further studies are still required on spontaneous conceptions, before this test can be recommended for routine clinical application.