35 weeks and waters breaking

[Deedles]

Hi, I have just found out that my SIL's waters broke last night around 12am and she is only 35 weeks.
She told me that she is on steroids for bubs and taking tablets to stop the contractions.
I know 35 weeks is pretty safe, but is there anything to specially worry about.

Also they want her to stay on bed rest for the next 4 days until she is at least 36 weeks.
Doesn't your waters breaking mean that there is a chance of infection? I know that the waters keep refilling. Though when I was in labour with DS1, my waters broke first and 20 hrs later when he wasn't born they gave me antibiotics due to the chance of infection. So how long can she wait with her waters broken?