Spin Class while Pregnant

I started taking spin class at the start of November right after my second miscarriage. I wanted something that got me in shape and worked with my schedule.. needless to say I am pretty obsessed. I go about 3 times a week

I just found out yesterday that I am pregnant again (woohoo!).. I am only about 3 weeks along. I know spinning is fine for pregnancy but I am wondering how long other people on this app are typically comfortable spinning? Do you wear a heart monitor? I went this morning and of course felt fine.