Long ago, when I was born, my mother was unable to provide enough breast milk for me and I was still at my birth weight at 6 weeks. The response then was to weigh me before and after breast feeding and top up with formula milk.
I am not recommending this. Just reporting practice in the past. I am with everyone else in saying that the mother has taken medical advice, so the problem is noticed and in hand, so step back and do not offer any opinion.
I am nearly 80 and still going strong, fit snd healthy and not on medication, so my failing to thrive for a couple of months clearly did me no harm.
Little House on the Prairie - Netflix


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