I’m going to do a little series here on basic skills for providing human milk to babies who are struggling to latch. Given the plethora of existing high-quality content out there, I’ll include a lot of links : )
Remember the WHO recommendation for supplementation:
Mother's Own Milk (MOM)
When MOM unavailable, pasteurized human donor milk
When MOM and donor milk unavailable, infant formula
Until milk increases around day 3-5, the amount of milk expressed will usually get lost in a pump. Hand expression is much more effective both for collecting those first drops and for stimulating supply since your hand can compress and most parents feel like it’s more natural than a pump (read, more oxytocin is released, which helps push out the milk). Hand express within 2 hours of birth and about every 3 hours including through the night (at least five times during a 24/hour period with the longest gap between expressions no longer than 5 hours). The most critical night-time expression is between 1am and 5am.
If you are exclusively pumping for a premature infant who cannot take milk by mouth or is very inefficient at suckling, you may want to transition to an electric pump once your milk increases.
The right size flange is the one that is most comfortable and expresses the most milk. There really isn't a "best" approach to sizing... some research is saying smaller sizes may be preferable, some research is saying larger sizes are just as good. Basically, try them out and see. Your nipple changes size when the pump is on, so you really cannot just measure your nipple and do some math. Try them.
Prepping the breast and doing some hand expression to start can lead to more efficient pumping
For exclusively pumping parents, aim for 5 pumping sessions by day 5, increasing to around 7 per 24-hour period depending on your supply pattern and how effective your pump is. Make sure you are pumping at least once between 1am and 5am. This is a key biological time to tell your body you need to make milk. Make sure you do not go longer than 5 hours between milk removals.
A full supply is 750mls (about 25oz) per 24 hours for one baby. It usually takes about a month to reach full supply. Typically, babies consume 750mls per 24 hours ages 1-6 months, at which point they begin to get some solids. Breastmilk fed babies do not usually need to increase the amount they consume once they reach that target. Their frequency patterns will change, but the daily volume usually is pretty consistent. If you notice you have a full supply and your baby appears to be hungry after a bottle feed, check on the bottle feeding method and how quickly your baby is eating. It should still take around 15 minutes at least for a feed, since that’s how long it takes for the stomach and the brain to communicate to one another and signal fullness.
A great handout for storage guidelines is on the IABLE website
Healthy, term breastfed babies tend to take these amounts at each feed during the first week:
1 day old - 2 to 10 mL (0.4 - 2 tsp)
1 to 2 days old - 5 to 15 mL (1 – 3 tsp)
2 to 3 days old - 15 to 30 mL (3 – 6 tsp)
3 to 4 days old - 30 to 60 mL (6-12 tsp or 3-4 Tbls)
Exclusive Pumping All Things Breastfeeding Episode 104