"My husband and I have been trying to have a child, and today my
gynaecologist told me that I'm pregnant!" 

"What a coincidence," says the man . "I'm a chicken farmer, and for years
all my hens were infertile, but today they're finally laying fertilized
eggs."

"That's great!" says the woman, "How did your chickens become fertile?" 

"I used a different cock," he replied.  

The woman smiled and said, "What a coincidence..."