I had this with my first child (now a very healthy 4.5 yr old). It was very unsettling at first but we were referred to a specialist who monitored the rest of the pregnancy and it ended up being kind of cool to get more frequent ultrasounds and extra hand holding. The rest of the pregnancy was completely normal, I delivered on time and she was a good weight. Our ped was sure to check that her kidneys were functioning well after birth.
During my 2nd pregnancy, it felt so strange to NOT be monitored as closely -- everything was normal and I only had one U/S the whole pregnancy.
Anyway, best wishes to your friend. I hope the rest of the pregnancy is smooth and that all is well with the baby.