Almost 39 weeks and still working

I’m 39 weeks Wednesday and I can’t hardly take working anymore. I told my manager to make my last this Saturday but I can’t take it anymore. My body feels super exhausted I’m already scheduled to work all week and I’m ready to start calling in but I don’t call in and I’ve been here for about 9 months and I’m ALWAYS here when I’m scheduled and ill feel bad if I were to start now. What should I do? Get a doctors note first? Tough it out till Saturday? I’m due on February 28th and I really tried to continue working but my body is so over it.