@terrywinkle So there’s really no good studies on this question (ie how much breast milk provides “benefits”). The general consensus is that breast milk provides the most benefits during the first 4-6 months of life.
Pumping is hard work! And for twins nonetheless. For me personally, based on the research and consultation with my doctor and husband (ER doc), I ended up exclusively pumping for 5 months and then we transitioned to formula and solids. Based on my review of the research it seemed baby “benefits” most from breast milk during the first 4-6 months of life.
Reposting more or less the same thing I post every time in response to a post like this.
There is really no science analyzing combo feeding or what amount of breast milk provides “benefits” as almost all studies compare exclusively breast fed babies to exclusively formula fed.
Longer discussion below:
So there’s no actual science supporting X amount of breastmilk delivers “benefits”. Largely because most studies compare exclusively formula fed babies to exclusively breast fed babies. It’s also hard to measure because it’s unclear which “benefit” we would be trying to measure and how to decide how much breast milk to test (25%, 50%, a set ounce amount). It’s a real gap in the research that I think we all wish we had a better answer for. People usually cite to a Kelly mom article for the 50ml stat but she doesn’t provide any sourcing to back it up.
The AAP has a study that shows some benefits (table 2) using an “ever” vs never breastfed comparison but it’s not adjusted for socioeconomic status and therefore it doesn’t really make a lot of sense (like it doesn’t make sense that one instance of breastfeeding (an “ever”) would result in a 40% decrease of some disease).
https://publications.aap.org/pediat...ding-and-the-Use-of?autologincheck=redirected
What we do know from the sibling studies and PROBIT, is there is really no discernible or lasting difference in health or intelligence outcomes between formula fed and breastfed babies. So do whatever works best for you, your mental health and your family.
Here’s one sibling study.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4077166/
Breastfeeding rates in the U.S. are socially patterned. Previous research has documented startling racial and socioeconomic disparities in infant feeding practices. However, much of the empirical evidence regarding the effects of breastfeeding on long-term child health and wellbeing does not adequately address the high degree of selection into breastfeeding. To address this important shortcoming, we employ sibling comparisons in conjunction with 25 years of panel data from the National Longitudinal Survey of Youth (NLSY) to approximate a natural experiment and more accurately estimate what a particular child’s outcome would be if he/she had been differently fed during infancy.
Results from standard multiple regression models suggest that children aged 4 to 14 who were breast- as opposed to bottle-fed did significantly better on 10 of the 11 outcomes studied. Once we restrict analyses to siblings and incorporate within-family fixed effects, estimates of the association between breastfeeding and all but one indicator of child health and wellbeing dramatically decrease and fail to maintain statistical significance. Our results suggest that much of the beneficial long-term effects typically attributed to breastfeeding, per se, may primarily be due to selection pressures into infant feeding practices along key demographic characteristics such as race and socioeconomic status.
Additional easier to digest research here:
https://fivethirtyeight.com/features/everybody-calm-down-about-breastfeeding/amp/
https://freakonomics.com/podcast/how-important-is-breastfeeding-really/#:~:text=OSTER%3A%20One%20of%20the%20real,this%20if%20they%20want%20it.
For some more science: milk from 4 weeks through 18 months is extremely stable and suitable for babies in that age range. Very little nutrition changes during that age range for milk.
Milk matures by 4-6 weeks and is extremely consistent in nutritional composition from that point forward. Mature milk is incredibly stable during the first 12-18 months of life in terms of calorie, fats, protein, ect. What does change are antibodies and the like and that is usually in response to environmental factors, like if mom or LO has a cold or something.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3586783/#:~:text=A%20dynamic%2C%20bioactive%20fluid%2C%20human,%2C%20diurnally%2C%20and%20between%20mothers.
By four to six weeks postpartum, human milk is considered fully mature. In contrast to the dramatic shift in composition observed in the first month of life, human milk remains relatively similar in composition, although subtle changes in milk composition do occur over the course of lactation.
See also:
https://www.medela.com/breastfeeding/mums-journey/breast-milk-composition
By the time your baby is four weeks old, your breast milk will be fully mature. It’s rich in protein, sugar, vitamins and minerals, plus numerous bioactive components – such as hormones, growth factors, enzymes and live cells – to support your baby’s healthy growth and development.
From four weeks, the nutritional content and levels of ingredients in mature milk generally remain fairly consistent. But the composition of your breast milk can still change from day to day and feed to feed.
For an extended discussion of when statistically significant changes in breastmilk do take place (generally in prolonged feeding of 18 months plus) see
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6316538/