One of the frequently asked questions of breastfeeding is “How much milk should I leave my baby while we are separated?”

The answers that I’ve seen vary. The answer that I subscribe to is “The One Ounce Per Hour Rule”.  (Which could be better described as the 1-1.25oz/hour rule).

The one ounce per hour rule is based on the average daily requirements of a breastfed infant who will take in 25oz/day of milk. (This does not vary much between one and six months). While amounts might be more or less during exclusive pumping / bottle feeding, the “One Ounce Per Hour” rule is considered the standard for shorter periods of mother and infant separation.

This method is the “breastfeeding friendly” method that is most likely to lead to longer term breastfeeding success. Other methods that allow on-demand feeding from bottles or that follow amount guidelines for formula fed babies often lead to supply decrease and early weaning or supplementation of non-human milk.

I’ve heard a lot of moms say that they are anxious about the one-ounce-per-hour rule of feeding a breastfed infant while separated from mom. I understand it. I was anxious as a new mom, too, and wanted to leave MORE than my baby needed because it hurt to leave him and I wanted to make sure he would be happy and satisfied while I was away.

The thing is.. It’s not starving your baby and it’s not letting your baby go hungry. It’s something your baby is already used to. The supply in your breasts is not static. It goes up and down across the day. Your baby is already used to this.

Your baby eats the same amount each day between one month and when solids are introduced. (A bit more during growth spurts- but this should happen at mom’s breast, since her supply has to scale.) This amount for breastfed babies averages out to 25oz/day with some babies eating as little as 19oz/day. Your supply is not static across the day, it increases and decreases across the day, so baby learns to nurse more during high supply hours, and less during low supply hours (which are typically in the evening)

What the one ounce per hour rule does is it encourages baby to view the bottle feeds as “low supply”, and mom-feeds as “high supply” and baby nurses more with mom and less with the bottle. Baby’s needs are met, not exceeded. More than one ounce per hour means baby finds bottle = high supply, breast = low supply, and starts fussing for more bottle, less mom. This means mom is stuck pumping HUGE amounts of milk.

This causes problems because the pump is ineffective. It’s like trying to siphon water out of a well with a drinking straw. It’s tedious, it’s boring, it’s a pain in the butt. Mom’s breasts let down easily to an eager baby, and noooot so well to a pump. 1-2oz per pumping session is actually EXCELLENT output. If baby is downing 2oz/hour or more than one ounce/hour? Mom would have to pump constantly at work to make up for it.

Better to convince baby that the bottle has a rotten supply and that it’s easier to gorge off mom. Easier on mom, easy enough on baby, and baby’s needs are more than met with the ounce per hour.

Sources: Average Intake of Breastmilk (Kellymom)

*** Important caveat: As with all “rules” there are exceptions. If mom and baby are routinely separated from each other during ALL of the highest supply hours of mom’s day and are only together briefly, the one ounce per hour rule might not work and baby may need more frequent feedings during separation. View the rule as a guideline and as a possible warning sign that your caregiver is overfeeding the baby or giving bottles that are too large/too frequent. It may not be the amount that is a problem but the bottle size. Maybe baby will do better with more frequent 2oz bottles. Maybe your pumping sessions need to be longer or more frequent in order to get milk of the right composition for what baby needs while separated. Never follow ANY rule that doesn’t work for your child.