A fetal heart rate of 170 beats per minute is within the normal range for a baby at 12 weeks and 4 days of pregnancy. During this stage, the average fetal heart rate can range from 120 to 180 bpm. It is important to note that individual variations are common, so slight deviations from the average are usually not a cause for concern. However, if you have any concerns about your baby's health or if there are other symptoms present, it is always best to consult with your healthcare provider for further evaluation and guidance.