I wonder how a brooks saddle would hold up to pregnancy. If you were riding it throughout, maybe the leather would change with you. But if you had a hiatus, say for winter or morning sickness, the leather would be all wrong.

Good luck with the saddle issue, I hope it is just that you aren't accustomed to it. I'm sure Mr. Fanatizarre will go along with the need for a new saddle temporarily if necessary.