What is the appropriate way to express your best wishes to a woman who is having a baby?
(This is for a colleague, if there are different ways depending on different contexts please explain those, too).
A usual phrase to say is お体を大事にしてください (take care of yourself).
Another common phrase is 元気な赤ちゃんを産んでください (I wish you to have a healthy baby born), but some people avoid this phrase because it sounds as if a baby with a congenital disease were undesirable or unacceptable.
赤ちゃんが無事に産まれますように祈ります/願います
?