iGFBP-1 is a highly sensitive and specific diagnostic marker for PROM（Premature Rupture Of Membranes）.

Phosphorylated iGFBP-1 is one of the most prominent proteins in amniotic fluid after 3 months of gestation until before delivery. When the membranes rupture, iGFBP-1 in the amniotic fluid can leak into the cervix and vagina through the rupture of the membranes, becoming a detection marker for premature rupture of the membranes.