the other ladies are right. it's an old wives tale. at first my boys heart rates were 175-180 until the end of my pregnancy when they went to 150-160. my cousin had a little girl and she said her heart rate from the begining was 145-155.
it`s an old wives tale that if the heartbeat sounds like a train its a boy and if it sounds like a horse galloping its a girl or visa versa, its only superstition (sp?) and no medical stuff proves it.
good luck with your pregnancy
nothins con really tell the sex of your baby unless you have and u/s done but the heart beat is nothing its not gonna determine what the sex theres no proof in that trust me i kno my babys heart beat was in that area and im having a boy so the only true way of knowing is by u/s and only that so wiat and see what the doc has to say id even has your doc and see what he/she says