There are so many things that you truly don't understand until you become a mother. For instance, how easily offended we are by the most innocent of comments made by others.
One thing about being a parent, is we get the chance to be on both sides of this matter. More than likely, you have been on the offending side of the conversation. More than likely, feeling like an ass.
In some cases, I have even been offended when another mother was offended by me... I know, shut up. My friend's daughter was almost two at the time and she slapped my newborn in the face with a baby doll bottle. On instinct, I grabbed her hand just before she hit my daughter again and said, "NO," resulting in tears from her. Her mother--who, might I add, watched the entire thing without saying a word--was offended by the tone of voice I used towards her daughter... are you kidding me?
I wonder exactly what it is about childbirth that turns this...