Dental work while pregnant
I think you have to weigh the risk of the procedure against the risk of not having the procedure. Oral health is so important during pregnancy what with all the hormonal changes that affect our gums and everything else. Untreated dental decay can lead to systemic problems, even affecting birth outcomes. So if you have an urgent need for a procedure, I wouldn't put it off. But if it can wait, I'd wait. Is it possible to get a second opinion?
Just food for thought, I have a friend who fell off her bike and hit her head. She got a head x-ray, and she didn't know she was already pregnant at the time. That baby is 6yo and fine.
I agree with cieloazul. Needing a crown can have a wide range of urgency. In my early 20's I moved a few times, so I saw several dentists. I'm trying to remember how long it was from when a dentist first told me I would eventually need a crown for a filling I had gotten as a child and when I actually got it. I called the dentist who did the original filling (my uncle) and he told me if I went to 10 dentists I'd get 10 different recommendations. It was probably a few months to over a year before I got the crown because I needed my wisdom teeth removed and did that first. The crown was not urgent at first, but it was by the time I got it.