Customized fetal growth standards: rationale and clinical application.

Accurate assessment of fetal growth status requires the definition of an optimal standard, which represents the growth potential of the baby. Against this standard, individually 'customized' percentiles can be calculated. They improve the distinction between normal and abnormal, and help in our understanding and diagnosis of pathological fetal growth. This method can be used as a tool for epidemiological analysis as well as for prospective clinical monitoring.