Why Breastfeed?

Enthusiastic proponents of breastfeeding are constantly bringing up reasons why it’s important to nurse your baby, so I was surprised when looking at a webinar put on by the University of Albany Public Health Department today. The webinar, which was about community support for breastfeeding, spent little time on the good outcomes to be expected from breastfeeding, but went directly to issues like employer decisions that can help or hinder nursing mothers.

Personally, I am a breastfeeding enthusiast, and calculate that I’ve spent about 30 months of my life nursing. I agree strongly with the novelist Eudora Welty’s character who declares that “a woman never feels so good as when she’s got milk in her”. But I’m disturbed when I see claims made about breastfeeding that cannot be supported by systematic research.

So, why is it good to breastfeed? Well, it’s not because it raises the child’s IQ. The differences reported between breast-fed and formula-fed children’s test scores are so small that they are actually less than the variation you’d expect for a single individual to show on two separate test administrations. In addition, because educated mothers in the U.S. are more likely to nurse their babies, and because genetically-determined factors help people achieve high levels of education, it’s possible that breast-fed babies on average carry genetic material that helps to raise their tested intelligence--  thus, we could argue just as well that higher intelligence makes babies more likely to be breast-fed, as that breastfeeding makes them have higher test scores.

And it’s not because breastfeeding causes bonding, attachment, or any combination of the two. There are a number of ideas left over from the 1970s that emphasize skin-to-skin contact as a factor in maternal bonding (“falling in love”) with the baby, and obviously breastfeeding mothers are more likely to be skin-to-skin than formula-feeding mothers. However (and I say this cautiously because measures of bonding are so poorly developed), it seems that mothers’ attitudes toward their babies are about the same after a couple of weeks whether they breastfeed, bottle-feed, or use a combination of the two--  except for some bottle-feeding mothers who have been convinced that they are not doing the right thing for their babies. As for attachment, the great majority of mothers in developed countries have weaned their babies months before any clear signs of attachment appear; naturally, early experiences might influence later development, but there is no evidence that they do so in this case. Bowlby’s studies of attachment were done at a time when breastfeeding was relatively infrequent, but his measures seem to apply in pretty much the same way now as they did then. There are cultural and ethnic differences in breastfeeding in the United States, but no evidence that babies in groups that breastfeed less tend to have less secure or less organized attachment than babies in other groups.

Is breastfeeding physically beneficial for infants?  As is well-known, human milk contains antibodies that help protect against infections that occur through the gut, including not only gastrointestinal disorders but some other diseases like polio. Although babies are born with a supply of antibodies against diseases that their mothers have developed immunity to, in the early months they are not very good at mounting defenses against new diseases they may be exposed to. The mother’s milk allows her body to be an “auxiliary immune system” that is good at developing antibodies against new infections and passing the antibodies on to the baby. This means that breastfed babies have some advantages, especially because it is easy for them to become dangerously dehydrated if they have repeated vomiting or diarrhea. But on the whole, babies in developed countries, with access to modern medical care, clean water, heat for sterilization of bottles, and refrigeration of formulas, are not likely to suffer from being formula-fed--  provided that they do not encounter problems of formula production like those recently in the news from China. Babies in Third World countries, however, may suffer serious, even fatal, health problems if their mothers do not breastfeed.

Is breastfeeding physically beneficial for mothers? The baby’s sucking at the breast does stimulate contractions of the mother’s uterus and helps return the uterus to its pre-pregnant size more quickly than would otherwise happen.  Breastfeeding mothers resume menstruation months later than do bottle-feeding mothers, but this does not necessarily mean that they do not ovulate and cannot become pregnant. Breastfeeding for a year or more seems to reduce later breast cancer rates somewhat. But there can also be mild downsides to breastfeeding, and most nursing mothers occasionally experience clogged ducts (“caked breast”), sore nipples, or breast infections.

How about the family in general? Is breastfeeding beneficial or not? It is certainly cheap compared with formula feeding, and the savings in money can be put to good use by most young families. Breastfeeding involves less extra work during the early months, since there are no bottles or nipples to clean and sterilize. Bottle-feeding can appeal more strongly to fathers who otherwise feel left out of the mother-baby loop, although the bottle can contain the mother’s milk rather than formula. The impact of breastfeeding on the mother’s return to work after some months can depend on her employment and the time and situations that allow for nursing the baby or pumping milk; however, returning to work in the first two weeks, when the milk supply is not yet well established, will probably mean that breastfeeding will not go on for long.

Breastfeeding does provide some assurance that a baby is getting picked up and attended to as much as is needed. Most bottle-fed babies also get all the attention they need, but bottle-feeding does make it possible for parents or caregivers to skimp on attention by propping bottles for the supine baby--  a practice that is illegal in many states that regulate what goes on in infant day care. Only occasionally does one encounter a breastfeeding mother who limits the baby’s nursing time (I once met one who used a stopwatch!), because most nursing mothers know that more sucking means more milk being produced.

Breastfeeding also pretty much assures that parents respond to a baby’s communications. Because adults cannot easily know how much milk a baby has taken, they rely on the baby’s signals to let them know what he or she needs. Bottle-feeding parents can do this too, but they can also pay more attention to how much milk is left in the bottle  and thus have the option of attending less to the baby’s cues. There is one unique situation of this kind associated with breastfeeding: the breastfed baby indicates to the nursing mother when it’s time for the switch from one breast to the other. Most women nurse on both sides at each “meal”, and although they can feel that a breast becomes softer to the touch as it is emptied of milk, they really cannot tell whether the breast is producing the fat-rich hindmilk or whether it is close to dry--   nor do they know whether the baby is hungry for the hindmilk or would like to proceed to the more watery foremilk being produced by the second breast. The baby’s communication, letting go of one nipple and fussing until the sides are switched, is essential. Does this stress on communication during breastfeeding make any difference to the development of gesture and speech communication? As far as I know, this has never been studied systematically, but it’s not implausible.

Most nursing mothers find breastfeeding gratifying (or probably they would stop). It can be a wonderful quiet time during which nobody will bother you, and you and the baby can just peacefully do your thing. There are several other good reasons for choosing to breastfeed, but the extravagant claims about the benefits for babies in the developed world have not been supported by evidence.  Some possible benefits have never been investigated carefully. But, like most other things about infant development, it’s more complicated than it appears, and is not a miracle cure for every infant and family problem.