My daughter had been at the lower side for an entire year and then moved on to the average range. My pediatrician was not worried.
Reasons --
1) my daughter was born small and was right on her curve throughout,
2) my mother and I are both small statured, and my baby's weight was okay according to that,
3) my pediatrician said Indian babies are usually not that plump as kids elsewhere in the world, especially those on the curve.
The takeaway was to monitor her growth on the curve she started on instead of comparing her on a relative scale.
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