knock up

A shotgun wedding is a wedding that has to take place quickly, often because the woman is pregnant.

A shotgun wedding is a merger between two companies which takes place in a hurry because one or both of the companies is having difficulties.

knock up---informal not polite to make a woman pregnant

in the club
BrE old-fashioned if a woman is in the club, she is going to have a baby - used humorously
= pregnant

join the club also welcome to the club AmE
spoken used after someone has described a bad situation that they are in, to tell them that you are in the same situation