I think it's a question of some companies being REALLY REALLY cautious. There probably isn't totally definitive proof that it IS or IS'NT harmful to do either of these things - how would you set about doing a clinical study on something like that?
Which means, that even if there isn't a great deal of evidence one way or the other, a client could accuse your treatment of having caused problems, and it could be hard to argue that you hadn't. Which might result in you being sued for lots of money. People are likely to get very upset if they think (rightly or wrongly) that someone were responsible for bad things happening to their baby. :Scared:
On a personal level (ie, i'm only speaking for what i would do) i think it might be best to abstain from treating them in case you ended up being held responsible for bad things happening.