Statistical methods for fetal monitoring with alpha-fetoprotein in maternal serum

Methods are presented for dealing with screening or diagnostic variables which exhibit trends over time. The number and spacing of observations is assumed to vary among patients. Criteria for establishing 'normal' trends, and for detecting extremes and pattern deviations, are developed. The methods are applied to a pregnancy study in which longitudinal data on alpha-fetoprotein in material were obtained in 1501 patients.