Nutrition and Pregnancy: Breastfeeding

A few weeks ago I promised I would write about breastfeeding, and now I am. Not having any kids myself, this isn’t a subject I knew much about (other than that breastfeeding is a good thing) until this term. And boy, have I learned a lot!
Breast milk is undoubtedly the perfect food for babies. How perfect? The nutritional content shifts over time to meet an infant’s changing needs, possibly due to symbiosis between mother and child. That said, breastfed babies almost always need iron supplementation, because breast milk is lower in iron than formula (especially with mothers who become iron deficient during pregnancy, which is common). Babies born with healthy iron stores can only draw off of them for 4-5 months before becoming deficient themselves, and that’s bad for brain development! Many babies also need vitamin K supplements, and pre-term babies may be deficient in zinc.
The role of probiotics (good intestinal bacteria and other microbes) in health is hot, hot, hot right now, and formula manufacturers are on the bandwagon. Get this: Breast milk contains at least 132 types of probiotics (which will vary from woman to woman), while infant formulas contain only a fraction of that.
Breast feeding is natural, but it doesn’t always come naturally. Women in the United States often need to be taught to breastfeed, because we don’t grow up seeing breasfeeding in progress, generally. The top concerns by new mothers are sore nipples and poor milk supply, both of which can be due to poor latching by the baby.

  • When the baby has a good latch, its mouth is open wide (like someone about to take a bite of a huge sandwich) and mom’s nipple disappears. 
  • When a baby latches the wrong way, the mother’s nipples often get sore and the baby doesn’t get enough milk. 
  • When a baby latches the right way, the mother usually feels fine and the baby gets enough milk. 
  • To keep milk flowing, the breast have to be emptied regularly, either through nursing or pumping. Use it or lose it!
The ideal length of time to breastfeed is at least six months, with the first four months being exclusive breast feeding (i.e., all of baby’s nutrition comes from breast milk). After four months, there’s no specific benefit to breastfeeding exclusively, so a mother can opt to start transitioning baby to a partial diet of formula, or to cereals and solid foods when baby is developmentally ready.
The first hour after birth is a critical window for breast feeding. While a woman’s breasts are structurally ready to produce milk around week 22 of pregnancy (which means mothers of preemies can breastfeed!), a few hormonal changes have to happen for milk to “come in.”

  • First, there has to be a drop in progesterone, which happens with the loss of the progesterone-secreting placenta during birth. 
  • Second, the new mother has to start secreting the hormone prolactin, which is stimulated in part by the very act of nursing. This is where that one-hour window comes in: when a newborn is placed on its mothers chest after birth, it instinctively goes for the breast, even though there’s no milk yet. But the baby’s stimulation of the breasts and nipples encourages release of prolactin, and the simple act of closeness encourages release of the hormone oxytocin (as do hugs!), which also encourages milk flow. 
  • (On a semi-related note, there’s a great TED talk on “Trust, morality and oxytocin” by neuroeconomist Paul Zak. Eight hugs a day!)
So when a new mother has a dip in progesterone and a rise in prolactin and oxytocin immediately following birth, milk generally comes in within 2-3 days (yes, baby can go that long before eating). For a long time, it was a bit of a mystery why women who had cesarean sections often had delays in milk production. Turns out it’s because mother and child are separated after birth! (Breast feeding-friendly hospitals make a point of getting C-section babies to breast within an hour…even in the operating room!) This can also be an issue with diabetic moms, because their newborns are often whisked away for observation.
I think this is the end of my Nutrition and Pregnancy series, unless anyone has specific questions. To wrap things up on a fun note, I’ll leave you with this excellent but not-quite-work-appropriate video on breastfeeding. Enjoy!