Rower enthusiasts, advice please!

Hey ladies Im almost 11 Weeks along now. Ive been rowing and running for a few years now and I know we're suppose to stay between 140-150 hr during pregnancy. I did slow my pace and shorten my runs, but honestly, at that pace I feel like Im exercising for nothing. Its just too damn easy. Its actually easier to pace myself on the rower, but on certain intervals I reach about 160-170 for 2-3 min before getting down to 130-140. Am I putting my baby at risk? Otherwise I really dont see the point, a speed walk would actually be more efficient. What do you people think?