Intrauterine growth restriction

A 28-year-old woman gravida 2, para 1, at 30 weeks gestation is seen in the obstetrics clinic. She was diagnosed with preeclampsia at 28 weeks gestation due to hypertension and accompanying proteinuria. At her visit today, her temperature is 37.6°C (99.7°F), pulse is 88/min, respirations are 14/min, and blood pressure is 149/85 mm Hg. She denies any headaches, visual disturbances, seizures, epigastric pain, swelling, bleeding, or dyspnea. During physical examination, the fundal height is measured at 26 cm (10.24 in). Which of the following tests would be most useful in evaluating the fetus for complications of preeclampsia?