"knock up" --usage

[FRITZ JUENGLING]

Recently I was at a  church picnic. I was standing around with my wife and several other people chatting about the usual stuff.  One of the women, about 30 years old, in the group was pregnant.  A man, about 50, came and joined the group and the first thing he said was, speaking to the pregnant lady "Well, I see you got knocked up!"  He thought he was quite (in the American sense of the word) funny.  I thought that remark was extremely rude and inapropriate.  My question, am I just a prude or was this really just the remark of a jerk?
Would appreciate any comments.
thanks,
Fritz