Is it reasonable??

I just got a new manager, and I know they are still learning the ropes. I know that hours are kinda tight, but I know they are perfectly capable of hiring another person. I am pregnant with my first and it has been a pretty rough pregnancy so far. I finally hit my second trimester, but I am still very sick most of the time. I really struggle to keep food down and my heart burn is absolutely insane which also makes me sick. I work a mixture of graveyard shifts and filler shifts where I am needed. My new manager has been good about trying to make everyone happy. I only ask for 1 day off a week. I am the only staff that works 10,11, and 12 hour shifts. Would it be reasonable to ask him to please not schedule me more than 9 hours in a shift? It’s just really difficult on me at the moment.