When Penny is suggesting ideas to celebrate Bernadette's pregnancy, one of her suggestions is hanging around in the hot tub and Bernadette says her doctor said she can't do that. In the previous episode, Bernadette and Howard were planning on going in the hot tub on Valentine's Day and Bernadette was planning on telling Howard she was pregnant.
At the beginning of the episode, it's revealed that Bernadette thinks she's pregnant because of the results of a home test. That means, she hasn't been to the doctor yet to confirm it. So, after Valentine's Day, she probably saw a doctor who told her that a hot tub would be bad for her.
At the beginning of the episode, it's revealed that Bernadette thinks she's pregnant because of the results of a home test. That means, she hasn't been to the doctor yet to confirm it. So, after Valentine's Day, she probably saw a doctor who told her that a hot tub would be bad for her.