Please note mommy, just because "payat" si baby doesn't mean na hindi sya healthy. Breastmilk is still the best for babies para maging mas healthy.
Ang size ni baby ay naka depende sa size ni mommy and daddy niya, kung both na payat ang parents talagang payat si baby. Pero kung payat ang isa at mataba ang isa, possible na maging payat or mataba si baby.
Mas okay siguro kung magpa check sa Pedia para sure kung underweight si baby or that's the normal body of their baby.