The efficiency of first-trimester serum analytes and maternal characteristics in predicting fetal growth disorders. 
To evaluate the association between first-trimester serum analytes, pregnancy-associated plasma protein A and free beta-human chorionic gonadotropin, and fetal growth disorders, and to determine whether a prediction model for these growth disorders can be developed.  Retrospective cohort study of patients seen for first-trimester aneuploidy screening.  Pregnancy-associated plasma protein A and free beta-human chorionic gonadotropin multiples of the median were evaluated for association with small- and large-for-gestational-age infants in combination with maternal characteristics.  Univariate and backward stepwise logistic regression analyses were performed and the area under the receiver-operator curves used to determine the best prediction models.  Neither pregnancy-associated plasma protein A nor free beta-human chorionic gonadotropin levels were associated with an increased risk of large-for-gestational-age infants.  For small-for-gestational-age infants, the final model included black race, free beta-human chorionic gonadotropin multiples of the median >90th percentile, and pregnancy-associated plasma protein A multiples of the median <5th percentile as significant predictors (area under the curve = 0.58).  Low pregnancy-associated plasma protein A and high free beta-human chorionic gonadotropin levels are associated with a small-for-gestational-age growth pattern; however, additional factors to improve the prediction model are needed.