You must decide how you want your baby to be fed while you are away at work.
If you begin working before he is four to six months old – that is, before solids are introduced – you will need to plan. Introduce a routine so feeding times are predictable and constant. If you feed your baby at breakfast and around 6:00 P.M., the person who looks after him during the day need give only the expressed milk or formula for the other two day-time feeding.
If you don’t want your baby to take any milk substitutes, freeze expressed breast milk; it will keep for up to six months in the freezer. It should take around two weeks get into his routine. You will need to decrease your daytime milk production before returning to work or you will be uncomfortable during the day.