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OUR BABIES, OURSELVES PART 6: The Biology of Breastfeeding

by Sarah on February 23rd, 2011

Here is some really interesting info from Chapter 6 of Our Babies, Ourselves. Some of it you may already know.

  • Women manufacture milk in a process called lactogenesis – by absorbing water, salts, sugar, and fat from the blood. (p.187)
  • The aureole has glands which produce sweat, lubricating the nipple to prevent soreness and which emits an odor that probably helps the baby find the source of the milk. (p. 187)
  • Colostrum is high in protein, low in sugar and fat, and has lots of lysozymes and immunoglobulins – the perfect combination to protect a newborn. (p. 188)
  • If a newborn doesn’t breastfeed within four or so days after birth, a mother’s levels of the prolactin hormone falls and milk production eventually stops. It means that there is a window of opportunity to connect with a baby and to get the nursing process going. (p. 189)
  • The more a baby sucks, the higher the levels of prolactin in the mom, and the more milk is produced. (p. 189)
  • The first milk to come out is “foremilk”. It is left over from previous feeds. It changes composition while it sits behind the nipple, starting out as high in fat, but the longer it sits, the more fat is absorbed back into the moms body, and the lower in fat the foremilk becomes. Babies need to have long feeds so that they drink both fore and hindmilk. The fore is good for thirst, the hind is good because the fat is what satisfies the baby. (p. 189)
  • Short feeds, combined with interval feeding (long gaps between feeds such as routines dictate) produce watery feeds with not enough fat and so babies are left feeling unsatisfied. (p. 190)
  • The let-down reflex, where the milk flows to the nipple, is influenced by outside forces and the mother’s state of mind. So, anxiety about breastfeeding can be s self-fulfilling prophecy. (p. 191)
  • Primate lactation and pregnancy are both well protected against times of scarcity. Pregnant women only need an extra 14% calories a day to support a developing baby, and breastfeeding women need an extra 25%. This shows that women are very resilient to decreases in the quality and quantity of food, and so babies can survive in and out the womb in times of famine. (p. 192)
  • The composition of milk is finely tuned to the growth and maturational needs, and the digestive system, of the young of each species. (p. 192)
  • It takes human babies 20 minutes to digest breast milk, and 4 hours to digest formula made from cow’s milk. (p.193)
  • Human milk contains about 100 amino acids, vitamins, and minerals (like salts and sugars), to perfectly meet a baby’s needs. (p.193)
  • Species where babies are left alone for long periods, produce milk which is high in fat and protein. The fact that human milk is relatively low in fat and protein shows that breastfeeding is intended to be more “continuous”. (p.193)
  • Babies are born with some antibodies in their systems which they received from their mom via the placenta, but it is only when they are five that their immune system fully develops. Colostrum and then breastmilk are the best sources of viral and bacterial protectants from between prenatal life and later life. (p. 194)
  • There is evidence that breastfed babies mature their own immune systems faster and more strongly than babies who are fed artificially. (p. 195)
  • Several studies show that breastfed babies seem to score higher on cognitive tests as babies and as older children. It is hard to tell whether this is because of the milk alone, or as a result of the maternal style that breastfeeding mothers offer. (p.197)
  • Continuous breastfeeding stops ovulation and prevents contraception. (p.198)
  • Women who were never breastfed themselves, and who never breastfeed as adults, are at higher risk for breast cancer than women who did both. The mechanism of this protection is unclear, and of course genetics play a part, but it seems that because breasts are supposed to go through certain hormonal and physical changes, if they don’t, they may become vulnerable to cancerous mutations. (p. 198)