How can u work when ur 8months pregnant

So I know a lot of girls that work from eight months pregnant and nine months till they pop and I know some girls that don’t even last that long and take off work when they’re five months pregnant . I want to kniw how they do it because im scared i cant make it all the way...and i need to work because im a single mom. This willl be my first pregnancy and i want to make it til i pop and be working