most articles I've read seem to suggest that you can if you are already an established runner, and continue your existing regime.
A different thing, though if you are only just thinking of taking it up - mostly I think you are adviced not to start a strenous exercise regime once you are pregnant.
I've always felt far too sick to carry on, though, so I've always had a break when pregnant ;(
think it is largely a personal thing.
have a search of articles on this site, I 'm sure that there has been one recently on pregnancy.
