The development of an index of high-risk pregnancy.

Presented is a scheme by which an index of high-risk pregnancy can be evaluated. The proposed scheme is applied to a risk index developed for the purpose of illustration. The usefulness of risk indices (or any other predictive measure) can be judged in clear statistical terms. The illustrative model developed here behaves similarly with each of the two sets of data on which it is tested, except to the extent that it is influenced by the incidence in the test population of the outcome to be predicted. The conclusion reached is that unreasonable demands are made of high-risk indices, that no index can satisfy all requirements. However, if the requirements are reasonably stated in advance, indices of high-risk pregnancy can be extremely useful.