If a newborn goes 5 hours without eating they may not gain enough weight fast enough and it could lead to malnourishment and poor weight gain.
If the newborn has not woken up in 5 hours to eat, you should wake your newborn to feed them, especially in the first couple weeks of their life, so that you ensure the newborn regains birth weight and gets enough nutrients, as newborns have tiny stomachs and require frequent feedings at least every 2 hours to 3 hours for proper growth.
Although a healthy and growing baby may be just fine with a slightly longer stretch between feedings, if the baby is otherwise alert and having enough wet and dirty diapers.
Going too long without eating in newborns and babies can slow weight gain, risk the baby developing jaundice and cause low blood sugar, so consistent feeding of your newborn is crucial for development.
Although at 3 weeks, it's usually fine to allow your baby to sleep up to 5 hours without waking for feedings as long as the baby is gaining weight.
Newborn babies often need to eat or be fed at least every 2 hours to every 4 hours.
Newborns should not go longer than 4 to 5 hours without eating, because newborns have small stomachs and the newborns body needs regular nourishment to grow and develop properly.
If your newborn is sleeping longer than 4 hours to 5 hours without feeding, then it is important that you always wake the newborn up to feed them.
When your newborn is hungry they will often cry, and root "turn their head towards the feeding source", suck on their fists or fingers and make sucking motions with their mouths.
In rare cases a newborn may be able to a bit longer without eating if the newborn is eating formula that is specially designed for newborns that sleep longer.
More than 5 hours is considered too long for a newborn to go without feeding and 7 hours is most certainly too long for a newborn to go without feeding.
You should feed your baby as often as they want to eat and for as long as they want.
Your baby will begin to have fewer, but longer feeds after a few days.
As a very rough guide, your baby should feed at least 8 to 12 times, or more, every 24 hours during the first few weeks.
If your baby or newborn baby doesn't eat for 7 hours it can be a sign of illness, infection, or low blood sugar.
Infants dehydrate easily and not eating can quickly turn into a medical issue.
Generally, babies shouldn't go without feeding for longer than five hours for their first 12 weeks.