Wednesday, January 30, 2013

Who manages the mammaries?

One of the really excellent points that have come up in the recent discussions of medicine failing breastfeeding is an appreciation that human breasts, like all other organ systems, can have physiological dysregulation and difficulties. There are a small percentage of women with physiological inability to produce milk (estimated at 2-5% of the population), just as there are individuals with beta cell dysfunction (Type 1 diabetics), thyroid issues, and problems with really every other organ in the body. By comparison, including types 1 & 2, the incidence of diabetes was 8.3% in 2011 (CDC, 2011). To put it simply, breasts are organs, and have about the same rate of physiological issues as other organs (I borrowed this from the ongoing conversations). 

However, there has been a tremendous increase in recent years in the number of women diagnosed with insufficient milk syndrome (or insufficient milk supply syndrome) or “low milk production”.  While there was an overall consensus the problem was becoming more common, concrete data were hard to find.  The best I can do is the Infant Feeding Practices Study from 2006, wonderfully indexed on I recommend checking it out, as you can see tables for every possible variable and even download the raw data. But, here are the numbers:

Month stopped breastfeeding
Reason for stopping breastfeeding 3
< 1
1 to 2
3 to 5
6 to 9
My baby had trouble sucking or latching on
Breast milk alone did not satisfy my baby
I thought that my baby was not gaining enough weight
A health professional said my baby was not gaining enough weight
I had trouble getting the milk flow to start
I didn't have enough milk
Table 1: Reasons for breastfeeding cessation, as reported by US women participating in the 2005-06 Infant Feeding Practices Study. More than 2500 women participated in the initial survey; approximately 1400 women completed the survey through the first year (Shealy et al., 2008).

I think, based on the numbers presented above, it is reasonable to say that of the number of women who stopped breastfeeding during the first five months of life, more than 50% identified insufficient milk supply as a contributing factor. While this is not an overall incidence, it does support the overall idea that IMS is increasingly common.  We can also not know the number of women who were told this by a medical professional versus self-diagnosed. If we use medical diagnosis of poor infant weight gain as a measure of medical diagnosis (again, not ideal) we end up with 8.6-19.8%. Still, much higher than the 2-5% who likely have actual insufficient milk supply. 

There are numerous physiological conditions that are associated with decreased milk supply, and we cannot discount that the increase in the incidence of these conditions may be contributing to the increase in the number of women with insufficient milk syndrome. These conditions include: polycystic ovarian syndrome; maternal postpartum hemorrhage, retained placenta/placental fragments, thyroid conditions, insufficient glandular tissue (Anderson 2001; Willis and Livingston, 1995; Speller and Brodribb, 2012; Neifert et al., 1985 – in topical order), and mammary reduction, although this is not an exhaustive list (refs). Other conditions, such as obesity and diabetes may also interfere with lactation (Turcksin et al., 2012), particularly the onset of milk production, known as lactogenesis (Nommsen-Rivers et al., 2010). 

However, while these biological conditions may explain the initial 2-5%, and perhaps a small increase in the incidence of these conditions, it is unlikely they explain the dramatic difference we see in Table 1, with more than 50% of women who stop breastfeeding by five months reporting problems with supply.  Based on the 2009 Healthy People Data (released in 2012), 76.9% of women are initiating breastfeeding and 47.2% of infants are breastfed to 6 months! So of the babies who start breastfeeding, 61.4% are still breastfeeding at 6 months (but only 47.2%) of all infants. And, extrapolating from the 52.6% (average over the 3 categories) of women who report lack of milk as a reason for breastfeeding cessation, we end up with a crude estimate of 32.3% for IMS. Again, this is a crude estimate based on linking several different sources of numbers together and should be considered an approximation, not a set in stone number and should be viewed as a “back of the envelope calculation”. I’m using it as it is better than anything else I can find (if you know of something let me know and I will adjust the post accordingly). 

So, we have an estimated occurrence of IMS at 32.3% compared to an estimated biological frequency of 2-5%. That’s an excess of 27.3-30.3% women reporting low milk supply. Add in the nearly 4 million infants born in the same year, and we’re talking about more than 1 million women identifying with low milk supply.
It seems unlikely then, that this difference can be explained only by physiological issues, even adding in possible physiological factors with infants as well, including tongue tie (Kumar and Kalke, 2012), palate, latch, or vacuum issues (Geddes et al., 2008; Geddes et al., 2012). Certainly, it would be an oversight to suggest that these factors are not very real, not uncommon, and not contributing to overall increases in IMS. But these factors along cannot explain the difference.

Difficulties with breastfeeding, including poor latch, poor positioning, pain, nipple confusion, nipple cracking/bleeding, mastitis, are very real realities for breastfeeding mothers.  How many of these issues are the result of limited exposure to other breastfeeding women and a medical community largely unfamiliar with breastfeeding issues? Osband et al., (2011) reported that pediatric residents in the United States received an average of 9 hours of breastfeeding education (over a 3 year residency). Anchondo et al., (2012), in a survey of pediatricians, obstetricians, gynecologists, and family medicine physicians, reported that although physicians in their study had positive attitudes towards breastfeeding and information on the health benefits, hands-on knowledge was considerably lacking. Physicians also reported low breastfeeding rates and short durations themselves. Freed (1995) in a survey of more than 3000+ medical residents and physicians (68% response rate) reported that while 90% endorsed breastfeeding, less than 50% felt like they had the skills for counseling mothers. And the scariest information: for treating jaundice, clinical management was wrong more than 50% of the time and for insufficient milk syndrome, wrong about 30% of the time.  

Nine hours of training, and probably a little extra (maybe a half day at most) of training during medical school, is the sum total of the “average” physicians training in breastfeeding. I would suspect too, that some of that medical school time is allocated towards mammary anatomy (not that this is not important for understanding how breastfeeding works). And the vast majority of that time will probably be fair more theoretical than hands on/practical, if the reports from Anchondo et al., (2012) are any indication.
The lack of training, and the invisibility of possible issues related to breastfeeding, may be contributing to those excess sufferers of IMS. How many physicians for example, upon hearing that a woman has “low milk supply,” will address the feeding and not the supply issue?  One of the most common “treatments” for low milk supply is to supplement the infant with formula. Here, the focus is on the infant, and meeting the metabolic needs of the infant, without thinking about how the situation could be addressed from the maternal side.  Milk production is driven by milk removal and suckling from the breast. A complex series of hormones and neuropeptides regulate milk synthesis, and include Feedback-inhibitor of lactation (FIL), oxytocin, and prolactin. Suckling stimulates prolactin release, and while plasma prolactin does not scale to milk synthesis rate (Cox et al., 1999), prolactin promotes mRNA synthesis and the production of milk proteins.  More suckling stimulates more prolactin and maintains circulating plasma levels and milk synthesis (Cregan et al., 2002). FIL works in a different manner – FIL accumulates in milk as feeding intervals increase and the breast becomes increasingly full; increasing FIL down regulates milk synthesis within the mammary epithelial cells (Peaker et al., 1998). 

By providing the infant with formula, the entire process above is interrupted.  Infant hunger is met by formula and the amount of time spent on the breast, actively sucking, decreases. The decrease reduces the secretion of prolactin, accumulating milk increases local FIL and milk synthesis is down regulated.  Production decreases, increasing the need for formula because the mother is now making less milk. It becomes a self-fulfilling prophecy and compounds issues that may or may not have been present. The ideal solution here would be to use the system, not disrupt it. Instead of supplemental formula, increase the frequency and duration (a minimum of 3-5 minutes) of the feeds.  Not enough milk? Feed more – in most cases, the body will respond accordingly. If it does not, and the infant starts losing weight, then there is likely more troubleshooting needed. But here, the clinical practice (30% of the time) is a wrench in the physiology and likely contributes to further development of low milk supply. Poor clinical management may not explain all instances of low milk supply, but it cannot be discounted as a major player.

Thus far, we have been limited the emphasis to frequently used clinical strategies for managing self- perceived low milk supply. Here, perception of low supply has driven a specific treatment; this has further contributed to the problem.  And that is just clinical management – what about other common problems influencing breastfeeding, on both the mother and the baby’s side of things, that contribute to low milk supply?

Next time (week): tongue tie, poor latch, and other breastfeeding challenges  . . .

Anchondo I, Berkeley L, Mulla ZD, Byrd T, Nuwayhid B, Handal G, Akins R. (2012) Pediatricians', obstetricians', gynecologists', and family medicine physicians' experiences with and attitudes about breast-feeding. South Med J. 105(5):243-8.
Anderson AM. (2001) Disruption of lactogenesis by retained placental fragments. J Hum Lact 17(2):142-4.
Cox DB, Owens RA, Hartmann PE. (1996) Blood and milk prolactin and the rate of milk synthesis in women. Exp Physiol.  81(6):1007-20.
Peaker M, Wilde CJ. (1996) Feedback control of milk secretion from milk. J Mammary Gland Biol Neoplasia 1(3):307-15.
Cregan MD, Mitoulas LR, Hartmann PE. (2002) Milk prolactin, feed volume and duration between feeds in women breastfeeding their full-term infants over a 24 h period. Exp Physiol. 87(2):207-14
Freed GL, Clark SJ, Lohr JA, Sorenson JR. (1995) Pediatrician involvement in breast-feeding promotion: a national study of residents and practitioners.  Pediatrics 96(3 Pt 1):490-4.
Geddes DT, Langton DB, Gollow I, Jacobs LA, Hartmann PE, Simmer K. (2008) Frenulotomy for breastfeeding infants with ankyloglossia: effect on milk removal and sucking mechanism as imaged by ultrasound. Pediatrics 122(1):e188-94. doi: 10.1542/peds.2007-2553.
Geddes DT, Sakalidis VS, Hepworth AR, McClellan HL, Kent JC, Lai CT, Hartmann PE. (2012) Tongue movement and intra-oral vacuum of term infants during breastfeeding and feeding from an experimental teat that released milk under vacuum only. Early Hum Dev. 88(6):443-9. doi: 10.1016
Infant Feeding Practice Study II., accessed Jan 24, 2013. Page last updated October 1, 2009.
Kumar M, Kalke E. (2012) Tongue-tie, breastfeeding difficulties and the role of Frenotomy. Acta Paediatr. 101(7):687-9.


  1. Excellent post. Would you illuminate the current understanding of the shift from endocrine to autocrine control of milk production that takes place around 3-4 months post-partum? I've always thought that the main culprit in true IMS was the cultural belief that babies only need to nurse every couple of hours, parents letting babies "cry it out" at night, and doctors' advice to moms not to "use their breasts as pacifiers." It's also probably the case that "I didn't have enough milk" is a culturally-acceptable excuse for moms to stop breastfeeding -- regardless of the true reason. By claiming that they didn't have enough milk, supplementing with formula and/or weaning becomes a route reluctantly taken by a well-intentioned mother who wants what is best for her child, and thereby avoids criticism from others. As opposed to saying "I didn't like breastfeeding" or "My husband wants my breasts for himself" or "My breasts were too big for me to play tennis."

  2. Katherine
    I am seeing that low supply or drop in supply more at 6 weeks but is it for the same reasons you describe above but parents are trying to get babies to sleep much sooner. I actually thought the endocrine to autocrine shift occurred quite a bit earlier.In The Core Curriculum for Lactation Consultant (2013) page 290 there are a number of references but they all appear a bit older (from 1993 to 1995. I would also like a bit more of an explanation on when this shift happens and what you see as occurring around that time

  3. This comment has been removed by the author.

  4. I also thought the switch from endocrine to autocrine occurred much sooner. I thought it occurred when milk supply becomes regulated by supply and demand rather than hormonally driven. Doesn't that occur within the first month or sooner?

  5. Hello everyone. I was beyond THRILLED to see our study quoted here, thanks E A Quinn! Anyway, I really want to know also what Dr. Dettwyler says about endocrine to autocrine. In teaching the undergraduate course here (TxTech) I used the info in the Riorden text, 4th ed., which says (don't have it here at home, but from my recollection)within the first few weeks. Of course this is very important to clarify due to the current controversy about cosleeping and (obviously) milk supply. Dr. Dettwyler?

  6. Hi Everyone,

    Lactogenesis stage 2 is usually complete by 72 hours; it is considered delayed lactogenesis if milk synthesis is not established by 72 hours. Part of the process is both the functional differentiation of the mammary epithelium as well as a shift in the hormonal signaling. However, Laurie Nommsen Rivers (2012) has some interesting work out suggesting that lactogenesis stage 2 may be delayed in American mothers up to 6 days (I think we can all hazard a guess as to why). I'll be addressing this in the upcoming post.

    Thanks for reading!

  7. Here's a good journalistic piece on Insufficient Glandular Tissue (IGT) you might be interested