Factors influencing how much milk you can express
Times to express
Breastfed babies (like bottle fed babies), will drink variable amounts of milk at each feed. Individual babies will also vary in how much they prefer to drink, and will need changing amounts of milk as they grow older. How much breast milk you will need to express to leave for your baby, can be a little unpredictable. It is for this reason that many women will divide their expressed breast milk into smaller 'portions', before freezing for storage. This avoids the need to discard large unused amounts of precious breast milk ('liquid gold') from being poured down the sink, because your baby was not hungry enough to drink it all (you can't refreeze unused milk). If you are unable to supply enough expressed breast milk for the time you will be away from your baby, you may need to make up the rest of their feeds with formula milk. (You can read about preparing formula in bottle-feeding).
The following volumes of milk are meant as a guide only. You should feed your baby 'what they need' and not be concerned if they do not finish all the milk in their bottle (or need more at times). If you want to read about the slow increase in milk volumes for very newborn babies during the first two weeks after birth (although the information relates to formula milk), you can read Class 11 - bottle feeding, the early days.
By a week or so after the birth, newborn babies born at term will generally drink about 150mls per kilogram of body weight, per 24 hours. Therefore, if your baby is about 4 kilograms in weight (or about 4,000 grams) they will drink about:
150mls x 4 kg = 600mls (in a 24 hour period)