Citation: http://www.straitstimes.com/BreakingNews/TechandScience/Story/STIStory_813022.html
It has already been clear that mothers' exercise wouldn't affect their babies' health, judging from the fact that we haven't yet heard many female athletes gave birth to children with something wrong.
I guess physical problems such as hitting against pregnants' stomachs would affect children's growth more clearly than chemical problems such as the example written in the article.