During anesthesia my mom almost drowned during my delivery she told me. why?

Various reasons: Word ' drowned ' is used when some one accumulates excessive fluid ( pulmonary edema ) due to several causes heart failure, excessive fluids, blood products, medications , reaction to drugs etc if it happened 46 yrs ago, current standreds of anesthesia is unbelievably safe, administered by highly trained and skilled professionals not same as half a century ago , .

Difficult to say: Would need more info. She could have aspirated contents from her stomach while general anesthesia was being given. Or she could have been given too much fluids in her IV and the fluid overload will cause fluid to go into the lungs. Getting the records would help.

Not Sure about this: I am sorry but this question is not really clear. If you mother was giving birth in a water bath i could understand the almost drowning comment. Otherwise there is a possibility that she vomited during delivery and this is what she is talking about. A pregnant patient is at increased risk from anesthesia due to the process that is going on, but these risks are manageable.