Friday Weird Science: Got nipple pain? Blame it on your vacuum baby.

So this isn’t necessarily weird science, in that it’s not something so odd and out there you’d never see it. It’s more that the reason behind the phenomenon is a little funny.
I’m at a time of life where all my friends are getting married. And once they get married, they start spawning. I’m a fan of friend-spawn, and I certainly hope that they all grow up to be adorable awesome little geeks. I will take any kind of geek, science, history, literature, music, theater, I love them all, and I know my amazingly brilliant and talented friends and fellow bloggers will produce some amazingly talented spawn.
Being as I am around such spawning, I’ve had the opportunity to learn a good bit about babies. And all the charming, cute, sweet, adorable, disgusting, smelling, and gross things that go with them. One of the things I became very quickly interested in was lactation. You know. Boobs and milk. Breast is best. I never realized before that there are lactation consultants. I always thought lactation was one of those things, like sex and giving birth, that people kind of figure out eventually on their own. Survival of the species and all that, you’d figure lactation would be pretty high on the list of things that come naturally.
But in fact, for many women, it doesn’t come naturally, and there are certain interventions that you can do to prevent pain and soreness during breastfeeding. But for some women, it seems that all the counseling and intervention in the world isn’t working. They have consistent pain while nursing. And now, we know why. The reason? VACUUM BABIES!
ResearchBlogging.org McClellan et al. “Infants of mothers with persistant nipple pain exert strong sucking vacuums.” Acta Paediatrica, 2008.


It may interest you to know that the sucking from the baby plays a very strong role in lactation in women. And lactation also has a lot to do with dopamine, a molecule of which I am very fond.
Basically, lactation works like this:
1) Baby sucks.
2) Mechanical stimulus from the sucking travels up from the breast to the spinal cord.
3) Neurons in the spinal cord headed to the brain, stimulated by the sucking, INHIBIT dopamine release from the arcuate nucleus of your hypothalamus (hypo=just below thalamus=your thalamus). This is a CRAZY important area of the brain that I think I’ll have to blog about sometime.
4) The moratorium on dopamine release removes inhibition on lactotrophs in the pituitary (also a CRAZY important area of the brain). Lacto=milk, troph=producing. These cells are normally under chronic inhibition via dopamine to stop them from stimulating milk, and when dopamine is inhibited, that inhibition is taken away, and milk production ramps up. Relief from chronic inhibition is one of those things which happens a LOT in neuroscience, I know it sounds like a curious twist of thinking, but you get used to it after a while.
5) Side note: suckling and lactation also stimulate the release of oxytocin from the hypothalamus. Oxytocin is a molecule implicated in pair-bonding (especially in voles), and in the formation of emotional bonds in general, and the hypothesis is that oxytocin released during breastfeeding makes bonding between mother and baby more powerful.
6) Side note #2: Stimulation of the spinal cord during breastfeeding also decreases GnRH release from the hypothalamus, which can inhibit the ovarian cycle. BUT. This is not 100% foolproof at all. So it is not a good idea to use lactation as your birth control, or you might end up with siblings extremely close in age.
Ok. That was really just an aside so I could talk about lactation, because I think it’s really interesting, especially all the things that can go wrong with it (for example, did you know that if you get REALLY bad whiplash from a car accident, it can shear your pituitary stalk, and lactation will cease? That’s really just one of the many life-threatening things that can happen when your pituitary stalk is cut, but it’s still an interesting fact). But this paper is actually about step #1, the sucking part.
Many women have pain when nursing. Often these problems are caused by infections, which can occur very commonly in the breast shortly after birth, or improper attachment of the baby, which can usually be helped with the aid of a lactation consultant. But for some women, no amount of help seems to clear up their nipple pain. This is bad, as pain will deacrease your milk production, and can also lead to early weaning, so the baby may not get as much of the beneficial effects of breastfeeding.
So this study looked at a set of women who experienced persistent, bad nipple pain, compared to normal controls, and looked at just how much of a vacuum was taking place when the were nursing. Basically, you can insert a probe in the corner of the baby’s mouth, the baby can still form a tight seal, and then you can measure pressure.
And what they found makes the most impact when you look at the lovely figure:
nipple.gif
LOOK at that on the left. Wow. What you can see is that mothers who experience a lot of nipple pain have babies which are exerting TWICE the sucking vacuum of controls. Ouchie. The pressure is much worse than that exerted by breast pumps as well, which hovers around negative 200. -200 is the peak of control babysucking power, and the vacuum babies take that and blow it out of the water. Poor moms.
So basically, if you’re having persistent nipple pain, this could well be due to your baby exerting strong pressure. Now, they didn’t really go into WHY the babies created more negative pressure. Stronger babies? Weaker brest milk production? The mothers with nipple pain produced less breast milk, but this could be an effect of pain, causing less expression, and thus causing the baby to suck harder. Or some women could have less milk expression making the baby suck harder and leading to nipple pain.
Unfortunately, though the mechanism is interesting, it doesn’t really give any ideas as to how to help these women. You can’t exactly ask the baby politely not to suck so hard. It could be that women with nipple pain like this could have to pump more and nurse less, as none of them experienced pain from the breast pump. It could also be a matter of starting the baby off on pumped milk and switching to breast halfway, so they will be full, and may not suck so hard, and less pain from it might allow more milk expression.
Whatever ends up working, I am all for putting the word “vacuum baby” into common usage among mothers. “Oh, little Edith is wonderful, but she’s a real vacuum baby!” I wonder if you listened, would you hear a vacuum sound? Would it be more like “woosh” or
“vvvvvvvvrrrrrrrrrrrrrrrmmmmmm”?
HL McClellan, DT Geddes, JC Kent, CP Garbin, LR Mitoulas, PE Hartmann (2008). Infants of mothers with persistent nipple pain exert strong sucking vacuums Acta Paediatrica, 97 (9), 1205-1209 DOI: 10.1111/j.1651-2227.2008.00882.x

10 Responses

  1. I never realized before that there are lactation consultants. I always thought lactation was one of those things, like sex and giving birth, that people kind of figure out eventually on their own. Survival of the species and all that, you’d figure lactation would be pretty high on the list of things that come naturally.

    HA HA HA HA HA HA HA HA!!!!! Um, no. Not in western culture.
    I think the lactation consultant represents a return to the way things were done up until 50 years ago when women helped other women learn to nurse. It’s hard and it’s not always very intuitive. The generation before us largely did not nurse and so we lost that continuity of knowledge and helpfulness. I think the lactation consultant plays an important in returning us to a place where women teach, help, and support other women who breatfeed.

  2. Soda straw. If a pressure probe is no problem, then just tape one or two short pieces of soda straw up to right next to the nipple. That should lower the pressure without interfering with the feeding.

  3. So, carefully following the logic of your article, if you breast-feed, then you’ll fall in love with voles. Perhaps we should stop calling babies “rug rats” and instead call them “rug voles.”
    More seriously, I’m interested in the dopamine inhibition. A brain low on dopamine is generally not a good thing. So, why does this nursing mechanism not cause a problem? Is the suppression of dopamine well-confined to a teeny-tiny region of the brain so there is no worry of low-dopamine problems elsewhere? Or does something else compensate?

  4. Emory: Well, I think the release of oxytocin in voles has to go along with copulation of the voles, so unless you’re willing to copulate…
    And yes, the inhibition of dopamine release is VERY local. I would in fact love to see nucleus accumbens levels of dopamine when mothers are nursing, I wouldn’t be surprised if there isn’t a certain amount of reward associated with it.

  5. Comrade PhysioProf thinks the hypothalamus is the most fascinating part of the vertebrate brain.

  6. It has been noted that anxious mothers experience difficulty expressing breast milk once their baby begins/attempts to nurse. I would be interested in finding out about the dopamine concentration changes in NA if that is the case.

  7. Sci: I would not do what you’re suggesting of my own volition.

  8. Janne,

    Soda straw. If a pressure probe is no problem, then just tape one or two short pieces of soda straw up to right next to the nipple. That should lower the pressure without interfering with the feeding.

    Hmm. That seems to me that it would reduce the pressure too far. Perhaps a much smaller straw, like a stirring straw, would do the trick. But even then I’m not so sure. If it did work, the mother would want to have the straw pointing upward so as to prevent milk/saliva from dribbling out of the straw.
    I still think, though, that a straw of any size presents too little an obstacle to the air flow, which would cause the pressure to drop too much. Perhaps a better option would be something to obstruct the seal without presenting a completely open path to the air, something like a bit of thick cloth, like felt. If the baby still went for the nipple with felt obstructing the seal, that is.
    However, I do wonder what the ingestion of a significant amount of air along with the milk would do to the poor kid. Might make burping a rather more difficult exercise, or it might make it so that the child is full before enough milk has been ingested. I’m just a physicist (and a male), so I can’t say what the biological effects would be.

  9. The generation before us largely did not nurse and so we lost that continuity of knowledge and helpfulness.

    Isis, dear lady, I am the generation before you and none (as in zero) of my contemporary acquaintances fed their offspring with anything other than what Nature provided [1]. Our excuse was that our mothers used formula — but in almost thirty years of asking around I haven’te found any of them who didn’t take the DIY route.
    I leave explanation of this curious phenomenon to others.
    [1] I except the brief period while my firstborn were unable to safely partake due to maternal medications.

  10. Janne,
    Straws? clothes?!
    The baby had to latch ON to the nipple.
    Picture trying use a soda straw with out closing you mouth around it. It just does not work.
    Getting the kid to latch on is the first step to learn with breast feeding.
    They gave me an ointment for sore nipples at the hospital, and my son keep slipping off.
    The ointment was tossed.
    I had to learn how to get him started and to then gently break the suction with a finger to stop. If I just pulled him off, ouch!
    The first little “vampire” I nursed wanted to spend all waking hours nursing.
    My doctor suggested cutting him off after 10-15 minutes, by then all reserved milk was gone. He would be feed again in an hour or two.
    My nipples were able to get a rest, after a few days the soreness went away.
    I was able to relax and enjoy nursing my baby for 2 years.
    Breasts are really marvelous things. For years, I had thought of them as ornamental.
    With birth they take on a whole other function. MIlk would leak out when I heard my baby cry. And then, after weaning, the milk production stops.
    Kathy K

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