In a prospective, blind study of 183 unselected women attending for routine booking scan with a singleton pregnancy at 16-24 weeks' gestation, uteroplacental resistance index, and peripheral levels of alpha-fetoprotein, human chorionic gonadotropin, human placental lactogen, Schwangerswaft protein, pregnancy-associated placental protein A and insulin-like growth factor (IGF) binding protein 1 were measured. High levels of alpha-fetoprotein and IGF 1 binding protein 1 (> 90th centile) were associated with small-for-gestational age babies (< 10th centile) (sensitivity 24% and 22%; specificity 90% and 91%). High levels of alpha-fetoprotein, human chorionic gonadotropin and pregnancy-associated placental protein A (> 90th centile) were associated with one or more of three severe complications of pregnancy: very small-for-gestational age (< 3rd centile), severe proteinuric hypertension or intrauterine death (sensitivity 20%, 20% and 57%; specificity 90%, 95% and 91%, respectively). A uteroplacental resistance index > 90th centile was also associated with small-for-gestational age and severe complications (sensitivity 24% and 50%, specificity 90% and 90%). A combination of resistance index and a placental function test improved the prediction for a group of patients that included any complications (sensitivity 31% and specificity 89%). Doppler ultrasound was a more efficient predictor than individual placental function tests but screening predictions can be improved by combining Doppler parameters and placental protein estimations. Combinations of placental function tests might provide equivalent, or complementary, information. This preliminary work demonstrates the potential value of combining biophysical and biochemical tests to predict complications of pregnancy.