What Causes Shortness Of Breath And Skipping Of Heart Beat?

I have always noticed brief moments where I cannot seem to catch my breath, but it is not as if I m winded. The only way I ve ever been able to explain it is that if feels as if someone stuck a vaccuum tube down my throat. This did not happen frequently & it would happen when I was simply sitting or standing, not exercising. Before, it was too brief to really think about. I would feel it happen, struggle to catch my breath, & then it would be over. I am now 3 months pregnant, & it happens more frequently & for longer amounts of time. I just now had the thought to put my hand to my chest to feel my heartbeat as this happened, & noticed that when this occurs my heart skips a beat and then starts again. What could this mean?