Could persistent nipple pain be caused by the strength of your baby’s suck?

barracudaUp to 90% of women experience nipple pain or soreness in the initial stage of breastfeeding, with the pain peaking in the first week, then gradually subsiding1. But what if, after 6 weeks, breastfeeding still hurts? You have been observed by what seems like hundreds of lactation professionals, and everything looks fine: your baby is latching on properly and you don’t have an infection. It simply feels to you like she is just a very ‘enthusiastic’ feeder, demonstrated by her toe-curlingly strong suck. Surely that couldn’t be the problem… could it?

Very little research has investigated the causes of chronic pain during breastfeeding, but one interesting study in this area has found a link between nipple pain and a baby’s ‘intra-oral vacuum’, or suck2. The study looked at two groups of women: 30 mothers who were experiencing persistent, unexplained nipple pain (without injury), despite help from lactation specialists; and a control group of 30 mothers with no problems breastfeeding. The vacuum produced by each baby whilst on the breast was measured using a small tube taped to the nipple and attached to a pressure sensor. The amount of milk the babies consumed was also measured, by weighing the babies before and after the feed.

The results were startling. The babies of the mothers who experienced pain when feeding exerted a vacuum when they were ‘actively’ sucking (taking in milk) that was more than 50% higher than the babies in the control group. In between these periods, when they were resting, the vacuum produced by the babies in the pain group was more than twice as high. Unfortunately, a stronger suck did not translate into more milk: babies in the pain group consumed on average 42% less milk, despite feeding for a similar length of time.

The cause of the lower milk intake wasn’t clear. There is a possibility that it was due to chance, or the experimental set-up, although the amount consumed in the control group babies matched that recorded in previous research, making this less likely. As pain can interfere with the let-down reflex, it’s possible that the simple fact that it hurt was enough to stop the milk from flowing properly3. This may in turn have affected milk production, as the amount of milk a baby consumes determines the rate at which it is produced4. It is important to point out, however, that all the babies in the study were gaining weight sufficiently, so the lower milk consumption documented in this single feed did not appear to translate into a more general nutrition problem.

The reason for the higher vacuum is also elusive. It may in some way be the effect rather than the cause of the restriction in milk flow, although this is purely speculative, and how and why this would happen isn’t clear. It’s also possible that the babies in the study may have been experiencing some other feeding difficulty that they compensated for with a stronger suck, although this had not been identified by any of the health professionals who had come into contact with them.

The study data indicate quite clearly that the women suffering from persistent, unexplained nipple pain had babies who exerted a significantly higher intra-oral vacuum on the breast when feeding. Although the data can’t prove the stronger suck caused the pain, it’s likely the two are related. Could this be the reason why for some women, breastfeeding never really seems to become comfortable? If you’re on the receiving end of high suction, then it’s easy to see how you could feel ambivalent about these results. On the one hand, it may be a relief to know that breastfeeding can be painful as a result of the way that your baby suckles, and not because of something that you are doing wrong. On the other hand, the prognosis may be a little disheartening, as it isn’t immediately clear how you solve a problem like this.

At present, such a diagnosis is unlikely, as intra-oral vacuum is rarely tested. The results of this study, however, suggest that in situations where chronic nipple pain has no obvious cause, that it probably should be (the authors certainly think so). Discomfort when breastfeeding is a difficult and stressful situation to deal with, and only with more research in this area can a cause (and hopefully a treatment) be identified. In the meantime, it seems that affected mothers need to carry on gritting their teeth, and perhaps reach for the pain killers…

  1. Acta Paediatr. 2008 Sep;97(9):1205-9.
  2. J Obstet Gynecol Neonatal Nurs. 2005 Jul-Aug;34(4):428-37.
  3. J Pediatr. 1948 Dec;33(6):698-704.
  4. J Exp Physiol. 1996 Sep;81(5):861-75.