Normal for heartbeat to drop?

I'm 16 weeks pregnant and the baby has always had a high hearbeat. It always stays between 180-150 the past 3 times I've used my Doppler thought its only been 130-145. Obviously I'm a bit concerned because I'm use to it being so high but my friend said that her baby did the same thing at about this time. Anyone else having this problem? Really makes me want to go to the hospital. But my nearest hospital with an labor and delivery is 45 mins away and they don't have their labor and delivery or er remodeled yet so its a mess and really hard to be seen.