The knowledge of a baby being big or small is just data, not meaningful information. Context is key.
Branding normal phases of development and transitions have become a thing, mainly to sell books more than identify any new discovery. That said, the first three months of a baby’s life after birth and mom’s postpartum period is a rather unique time for many reasons.
Ideology, not medical reality, has infected much of modern parenting. The most compelling pediatric articles -- centered around misguided activism that still persists -- focused on infant feeding, vaccines and mom-shaming.
When the American Academy of Pediatrics has to issue a report for pediatricians to write a "prescription for play" at every well-visit, our culture is in crisis.
The negative impact of (1) "at-all-costs" breastfeeding campaigns, (2) the political zeal of "lactivism" and (3) societal pressures have done a proven disservice to women and families. So much so that formal health policy had to be changed.