Also as for pace - what has helped me stay running - is realizing that the MPH really cuts down in the second trimester. I went from 7.5 MPH to 6.0 MPH. Then around 25 weeks I was doing 5.5 MPH. Now Im still around 5.5-5.2 MPH.
When I dip into like 4.5 (lol oh man I cant even fathom how laborious that will feel though) I will switch to walking (which a typical walk pace for me is 4.1-4.2 - but pregnancy my "fast" is 3.5 and average is 3.2 MPH if that helps