In all breast pump markets, one argument keeps coming back: "our device mimics your baby's natural suckling." But which baby, exactly? A 72-hour-old newborn? A 14-month-old whose orofacial muscle strength is completely different?

Scientific literature precisely measures neonatal suckling (0-8 weeks). For older ages: data is almost non-existent. This is the first article in French to clearly state this gap.

We didn't find this observation in a book. We experienced it firsthand in the field: through the Madame Tire-Lait training and feedback from over 5,000 mothers, we observed that pumping profiles designed for newborns yielded different results depending on the age of the breastfed child. Then, when we looked for literature to explain why, we realized it didn't exist yet.

That's why we designed Asymétrie with several levels of suction profiles. And that's why we're publicly documenting this gap.

The mechanics of lactation

Suckling → nipple nerves → brain signal → pituitary releases:

PROLACTIN: milk synthesis in the alveoli

OXYTOCIN: let-down reflex → milk ejection

Without the let-down reflex, milk doesn't come out, regardless of the suction strength.

An effective breast pump is not a strong breast pump. It's a breast pump that triggers the right hormonal signal.

Nutritive vs non-nutritive suckling

NON-NUTRITIVE SUCKLING (NNS) — stimulation phase Frequency: 100 to 120 cycles/minute | Pressure: 70 to 90 mmHg | Peaks: -145 ±58 mmHg

NUTRITIVE SUCKLING (NS) — expression phase Frequency: 40 to 60 cycles/minute | Base pressure: -31 to -64 mmHg | Peaks: -106 to -145 mmHg

Sources: Geddes et al. (2008) Early Human Development; Sakalidis et al. (2012) Int J Pediatr; PMC5991864 — Breastfeeding Diagnostic Device study (2018)

The actual scientific figures

Central discovery by Geddes & Hartmann: vacuum is the primary mechanism for breast milk transfer — not tongue compression.

On excessive pressure:

• McClellan, Geddes et al. (2015): -237.7 ±59.6 mmHg → reduces milk flow
• Perrella, Lai & Geddes (2015): -233 ±152 mmHg → severe pain + lesions
• Zinaman et al. (1992): pressure above normal → no benefit

Pumping harder doesn't yield more milk. Pumping harder can even yield less.

This is one of the central messages of the Madame Tire-Lait training: understanding what the breast pump does in the body, not just pressing "more."

What manufacturers do with this data

Note: Medela is cited here only as a source of published scientific research. No comparison with Lupa products. Bibliographic reference in accordance with art. L122-1 to L122-7 of the French Consumer Code.

PMC3212618 (J. Perinatology 2011): suction profiles mimicking term infants produce more milk in less time in mothers of preterm infants.

Two established phases:

• Initiation phase: high frequency, low pressure (NNS)
• Maintenance phase: 35-54 cycles/min depending on flow (NS)

Common point of all these studies: measurements on infants aged 0 to 8 weeks. No manufacturer claims settings in reference to the suckling of a 6, 9 or 12-month-old child — because this data does not exist.

The gap: what changes as baby grows?

This is the question no one asks — and that research hasn't answered.

A 4-week-old infant and a 14-month-old child do not suckle the same way.

Two anatomical mechanisms:

Development of orofacial muscles (masseter, buccinator, temporalis) → significantly strengthen in the first 12-18 months.

Evolution of the suckling profile → perfected suck-swallow-breathe coordination → potentially longer, deeper cycles, higher baseline pressure.

There is no published curve for the development of intraoral suckling strength by age group in the context of breastfeeding. This is a real scientific gap.

It is partly to address this that we document field feedback from the Madame Tire-Lait training: mothers at all stages of breastfeeding, with very different profiles — and consistent observations that the literature has not yet formalized.

Practical implications for your pumping

For a newborn (0-6 weeks): high frequency / low pressure settings correspond to the well-documented neonatal NNS zone.

For a child aged 4 to 12 months: your body has calibrated its response to the suckling of that specific child. A newborn stimulation profile may not send the same signal.

Field observation (not published science): some mothers report better let-down reflexes at slightly lower frequencies and slightly higher pressures with an older child. We honestly document this: it is not published truth.

Lupa's position

In Asymétrie:

• First levels: high frequency, moderate pressure → neonatal NNS
• Higher levels: lower frequency, deeper suction → profile corresponding to what is observed for an older child
• Upper comfort limit (manual unlock): because science shows that beyond a certain threshold, it is counterproductive

The design of this program relies on available literature AND on field feedback from the Madame Tire-Lait training. It is this cross-referencing — published science + documented field experience — that makes the difference.

Sources: [1] Geddes DT et al. Early Human Dev. 2008. PubMed 18262351 — [2] Ramsay DT et al. J Anat. 2005. PubMed 15960763 — [3] Sakalidis VS et al. Int J Pediatr. 2012. PMC3398629 — [4] Sakalidis VS et al. Early Human Dev. 2011 — [5] PMC5991864 BDD study 2018 — [6] McClellan HL, Geddes DT et al. J Hum Lact. 2015 — [7] Perrella SL, Lai CT, Geddes DT. BMC Pregnancy. 2015 — [8] Zinaman MJ et al. Pediatrics. 1992 — [9] PMC6866149 2019 — [10] PMC3212618 J Perinatol. 2011 — [11] PMC4920726 2016 — [12] PMC10204509 Biomimetics. 2023 — [13] USPTO US6383163 / US6306115 — [14] Geddes DT et al. Early Human Dev. 1997