What Causes The Echoing Of Heartbeat In The Ear During Pregnancy?

I am pregnant and can hear my heartbeat in my left ear and also a whooshing sound if I bedn down or move my head. I can get temporary relief by tilting my head to the right and also pushing my left ear to a pillow - thus muffling the sound. Also if I put an ear plug in tightly I can't hear the heart beat (but then also can't hear from this ear). My left ear feels blocked but sticking my little finger in the gap for a few seconds and pulling it out helps to clear it but only for a few seconds.I've had this for two weeks now and don't want it all through the pregnancy or longer so is there something an ENT can do? I'm assuming it's due to the increased clood flow from being pregnant, but I've also had a cold over the past fortnight and am congested and have been swimming more regularly over the past month. Thanks. I am 29, 5ft,1, weigh 58kg am 16 weeks pregnant and have had problems with my andenoids when younger (when I was 8) and a couple of ear infections in the past 12 years.