It is important to note that every baby is unique and may have varying heart rates during pregnancy. However, in general, a heart rate of 234 beats per minute at 18 weeks is considered within the normal range. The average fetal heart rate ranges from 120 to 160 beats per minute, but it can fluctuate depending on various factors such as activity level and gestational age. It is always recommended to consult with your healthcare provider for personalized guidance and reassurance. They will monitor your baby's development and ensure everything is progressing well.