Cranial Doppler ultrasound and the NNE-C examinations will be performed within 5 days after birth on full-term infants and at post-menstrual age (PMA) of 40 weeks (± 1 week) on preterm infants in the baby room. If the examination time occurs after hospital discharge, assessment will be conducted in the baby room at NTUH or in the ultrasound examination room at MMH. The examinations will be performed when the babies show stable vital signs in daily activities. The NNE-C examination will be administered one hour prior to feeding to minimize distress. The NNE-C examination will be performed immediately after the ultrasound assessment. The two examinations will be performed by different examiners who were blind to each other's results. During brain Doppler ultrasound examination, each infant will be placed on the back in a baby crib or an incubator with his/her head in midline. Infant's behavioral state will be kept in the behavioral state of 1 (quiet sleep), 2 (active sleep), or 3 (drowsy) on Brazelton's classification to eliminate the impact on cerebral blood flow velocity.