I found a list of a’mal which should be done during pregnancy at this link:
http://www.duas.org/Matrimony/pregnancy_safety.htm
But there doesn’t seem to be any original source to these recommendations (I spent a few hours looking for it on the net)
Do you know if these recommendations are indeed from Hadith?

by

None of them are but there is no harm in doing them as they are mostly derived from Quran