How often can a newborn baby pee?

Newborn bladders are very small, and their kidneys are unable to concentrate urine for the first couple of months, so in the earliest days young babies can wee up to 30+ times a day. But soon, in the next few weeks, you should expect about 9–12+ wet nappies each 24 hour (virtually a nappy change every feed). Frequent wet nappies are normal once the breastmilk is in and are a good measure of hydration. Infant urine should not be dark, bright yellow, or have a strong smell, because that probably means your baby is dehydrated, which should be treated seriously.