A 32-year-old primigravida at 28 weeks gestation presents for a routine antenatal visit. Fundal height measurement is 2 cm below the expected level. Ultrasound confirms estimated fetal weight at the 5th percentile with normal amniotic fluid volume and normal umbilical artery Doppler. The patient is asymptomatic with normal blood pressure and no proteinuria. What is the most appropriate next step in management?