How helpful is it to draw a distinction between nutritive and non-nutritive sucking in breastfeeding?

The distinction between nutritive and non-nutritive sucking derives from machine metaphors and doesn't help women breastfeed

There has been a longstanding distinction made by breastfeeding support professionals between nutritive and non-nutritive sucking.

However, this is a rather artificial distinction, which can be quite unhelpful.

The amount of milk transferred in a single suck depends upon

• Whether or not the mother has a milk ejection

• What phase of the milk ejection is occurring

• How much milk remains in the lactiferous ducts in the absence of a milk ejection.

If as clinicians we tell women that there is a distinction between nutritive and non-nutritive sucking, everyone starts to think that non-nutritive sucks are unhelpful, useless, or even a waste of time. We ourselves might develop the idea that non-nutritive sucks are a waste of baby's precious energy! Nutritive sucks, in this machine-like framing, are said to be necessary for successful breastfeeding and should be observed in the clinic (or even heard on ausculation with a stethescope. You can read elsewhere why cervical auscultation does not help breastfeeding women, and may hinder your clinical effectiveness.)

The belief that suckling wastes an (otherwise medically stable term) infant's precious energy resources or unnecessarily drives up caloric needs

• Derives from outdated reductionist or 'machine' metaphors of milk production and transfer

• Discounts the significance of sucking for an infant's sensory motor development. Abundant suckling experience is vital for downregulation of the infant's nervous system

• Inappropriately projects a concern that may have relevance for prematurely born infants in the Neonatal Intensive Care Unit onto breastfeeding support of healthy term infants, who face breastfeeding challenges.

Milk ejection is not a machine-like expulsion of milk

It's normal for some breastfeeds to transfer very little milk or no milk at all. What matters is patterns of milk transfer over a 24-48 hour period.

The milk ejection is not a machine-like expulsion of milk. It is not a timed, coordinated and pulse-like ejection of milk from the glandular tissue, in which all the breast's glands are full, oxytocin surges, all the glands empty.

Research from Professor Geddes' teams demonstrates that milk ejection is asynchronous across each breast. With milk ejection, ductal dilations and breast stroma pressure changes ripple out irregularly through the breast. Some parts of the mammary glandular tissue release more milk, other parts less.

Counting sucks and swallows can undermine breastfeeding success

Some breastfeeding support professionals even count sucks and swallows, believing this is clinically relevant - an indication of breastfeeding success or failure. Again, this approach derives from outdated machine-metaphors, which have typified 20th century lactation science and science more broadly.

21st century science teaches us that biological systems typically function in a way that is much more complex and random than this. There is usually a great deal of asynchrony, irregularity, and unpredictability inherent in biological systems, which are regulated overall by multiple feedback loops and dynamic adjustments around homeostasis over time. What matters with breastfeeding and milk transfer is patterns over time, not a snapshot in a single moment of time.

Although hearing and seeing a baby transfer milk in great successive swallows with a letdown (in the absence of pain, without fussing) is a great clinical sign, milk transfer in a single consultation is always contextual. My task as a clinican is to set up the context in which optimal milk transfer can occur (from the perspective of both fit and hold, and frequent flexible offers) as a pattern over a day or two (not necessarily in that particular observed breastfeed).

Suck-swallow-breath dyscoordination is most commonly the result of infant motoric instability

Professor Geddes and her team demonstrated in their research that suck-swallow and suck-swallow-breathe ratios are not rigid and predictable, but dynamic and variable over time.

Suck-swallow, and suck-swallow-breath patterns are highly variable when a baby is suckling at the breast. A baby with positional instability will appear to have suck-swallow-breath coordination problems, but this is entirely contextual, resulting from motor instability (not from innate breathing problems).

References

Lau C. Development of Suck and Swallow Mechanisms in Infants. Ann Nutr Metab. 2015;66 Suppl 5(0 5):7-14. doi: 10.1159/000381361. Epub 2015 Jul 24. PMID: 26226992; PMCID: PMC4530609. pdf under BF/biomechanics 2025 - not yet in Endnote