I can relate to your post very well, even though my kids are 29 and 26.
Exercise kept me sane through both pregnancies. I remember walking near the end of my pregnancy with DS 1, after I just couldn't do aerobics any more. It felt more like exercise than all the other hard stuff I had been doing.
I can't say how many times we have both said we have both said we wished we were into cycling when the kids were young, and we would have had them in a trailer.
And, my kids were born at 38 and 36 weeks, with no issues.