How much should your baby weigh?

At 33 weeks pregnant? My sister in law is 33 weeks 4 days measuring at 32 weeks 2 days. They’re saying the baby weighs 3 pounds 9 ounces so far and everything looks good. His oxygen is fine his heartbeat is fine. And he’s already head down. But they’re sending her to a high risk dr and I’m terrified for her and don’t know how I can help! The dr said not to worry too much but she is freaking out