Mine is 5 months and wakes usually once nightly between 3:30-4:30 am. Sometimes she will wake between 11- 1am also if her schedule was off during the day.
I know it's hunger for her, because of the timing and the way she screams. she is usually also wet, but can't wait to be changed. I bf one side, change diaper, then the other side and if she falls asleep that's ok (but often does not fall back to sleep till in her crib).