They can show symptoms as soon as they are born. Some are born with meconium ileus due to the thick sticky mucus and they are diagnosed straight away
suht.nhs.uk/OurServices/Child…
Others can be months or years old and have symptoms such as failure to thrive or constant chest infections.
Bloated stomachs and foul smelling nappies can also happen in babies.
it depends how severe the case of cystic fibrosis is.. if it is a severe case symptoms can appear as a baby but if it is a mild case they could appear in early childhood.