yes its totally normal. your whole body is "working" really hard when you are pregnant. youre producing more blood (for the baby), feeding the baby in your uterus ect ect... everything that happens in your pregnancy effects the heart. its working more than before. if though, your heart rate is getting too high and you feel strange/dizzy/light headed.. then please go to your doctor.
at 5:40 PM on Nov. 28, 2008