Methods of determining an increased risk of a woman carrying a downs syndrome affected fetus by measuring an analyte in a biological sample

The present invention relates to assay methods which allow for the detection, and quantitation, of analytes; such as, leptin and/or prorenin and/or renin, in biological samples, such as blood or urine from a pregnant woman, which are associated with an increased risk that the pregnant woman's fetus has Downs Syndrome. There are provided methods for assaying biological specimens for one or more of leptin, prorenin or renin in order to provide predictive information about the likelihood of a woman carrying a Downs Syndrome affected fetus.