Runnermum - Your post sounds very much like me. I was a swimmer for 14 years but I did give it up 8 years ago but have prided myself on somewhat keeping my swimmers physique. I put on 18kg with DS ad lost it without even trying after the birth and was back to my 63kg starting weight within 6 weeks of having him. Your metabolism is obviously very good so I think your body will look after itself after the birth.

Good luck and hope everything goes well.