When to stop working?

i'm currently 35 weeks. if i want to stop working at 38 weeks, do i just have to talk to my doctor and he signs the papers? or does there have to be more of a reason/medical condition other than impending birth in 2 weeks? also, i'm entitled to paid disability--6 weeks for l, 8 weeks for c-section. does anyone know if i get coverage if i stop working before the baby is born in addition to the 6/8 weeks afterward? i get coverage up to 26 weeks if my doc doesn't release me. thanks!