On average babies regain their birth weight by around two weeks after birth. Prematurity, birth history, jaundice, or illness can all slow weight gain. But an increase in weight after birth is important and importantly, shows that the baby is growing.
Babies gain weight when the amount of energy they’re getting in feeds exceeds their metabolic requirements.
Excess kilojoules are channelled into fuelling growth so that generally, there is a doubling of birth weight by 5-6 months. Head circumference and length also need to increase.
Breastfed babies are different
Breastfed babies gain weight differently to those who are formula fed, which is why there are different growth charts for each.
An average weight gain from birth to three months is around 150-200 grams per week, but this is dependent on individual factors, genetics and gender and is a guide only.
Common causes for slow weight gain are low milk supply and/or, the baby not feeding frequently enough.
Efficient, strong sucking is important to stimulate the mother’s breasts to produce milk and meet her baby’s demands.
But I don’t have time to eat!
When a mother is unwell, not eating or resting enough, this is likely to have impact on her supply. If the baby has been unwell, vomiting or not digesting the milk this too can affect weight gain.
Should I wake my sleeping baby?
Sleeping well is not always an indication that a baby is thriving. Babies can be sleepy when they are not getting sufficient milk and their sleepiness is a sign of dehydration rather than settledness.
Five or more wet nappies a day, good skin colour and muscle tone and periods of being alert, wakeful and responsive are all important. As is weight gain and tracking along the percentile (growth) curves for weight, head circumference and length.
When a baby drops down on their percentile curves then this is a concern.
Where to go for help
Child health nurses are experts in offering feeding advice and general information about babies and children. Check with your CHN to see how your baby is growing and developing.