Abstract: Assays, kits and methods for determining the presence or amount inositol phosphoglycans (IPG) analytes in samples are disclosed based on the finding that IPG antigens are capable of binding to gelatin. These assays can be used in the diagnosis of conditions where the presence or amount of these analytes is a diagnostic marker for a condition. Methods for the diagnosis of pre-eclampsia, distinguishing different type of pre-eclampsia, are disclosed and also methods for determining the onset of labour in a patient.