Should we tell my sister our friend got hurt?

My sister is in the hospital on bed rest for preterm labor and she is about 32 weeks. I know stress can make babies come early. Today our close friend Dennis we've known since we were little was sent to the same hospital as her. He got shot and isn't doing well and she really loves Dennis (as a friend) and doesn't know he's hurt. Should we tell her now or just to be safe should wait until the babies are born? What would you do