there are no specified working hours. I was 9 months pregnant during Ramadan last year. Its the normal working hours during Ramadan. But, as someone mentioned, pregnant women are exempt from not being able to drink or eat during the day.
In fact, I was stopped twice by the police drinking water in the car (I didn't do it completely in front, I dropped down a bit in the car to drink). One was still mad at me even though he could see I was pregnant.
And, with this heat, she needs to drink lots of water right now. Make sure she gets a lot of rest. I often left early just because even working through 4 hours was like I'd worked 20.
Good luck and congratulations!!!