Need a tip from runners please

[nosillies]

I do long distance runs on weekends. I was doing a 10 mile this last Saturday. At 8.5 miles, I stopped for a water break. I felt great, but when I tried to start going again -- thwarted! I felt a funny feeling on the outside of my knee. I walked and half-jogged the 1.5 miles back (fun). A PT I was running with said it was most likely my IT band, and to ice it. I did, and it eventually felt better.

My question: what can I do to prevent this on my next long run?

P.S. I am four months pregnant, so I realize I'm going to have some joint discomfort at times. Is this a joint-related issue?