Flat nipple. Inverted nipple. Umbilicated nipple. These terms are often used, sometimes interchangeably, but incorrectly. Each corresponds to a different anatomical reality, with distinct implications for breastfeeding, nursing, and pumping.

What makes this topic even more rarely well-addressed is the specific impact of these anatomies on the breast pump. You're told that nursing will be difficult. You're told about nipple shields, positioning, and latching. But what you're almost never told is that your breast pump, used correctly, at the right time, with the right flange, can literally change everything from the first hours of your baby's life.

I'm Roxane Bondu, founder of Lupa Allaitement. I myself have inverted nipples, surgically corrected with all the consequences that entails for pumping. I'll explain everything: the theory, the science, and what it actually means in practice.

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Table of Contents

1. Flat, Inverted, Umbilicated Nipple: What's the Difference?
2. Grades of Inversion: 1 to 3, What it Changes
3. What Corrective Surgery Can — and Cannot — Do
4. My Story: Inverted Nipples, Surgery, Piercing, and Breast Pump
5. What it Changes for Nursing
6. The Breast Pump: A Tool for Preparation and Eversion Before Nursing
7. How to Measure Your Nipple When it's Flat or Inverted
8. Flange and Non-Protractile Nipple: What You Need to Know
9. What to Do at the Maternity Ward — and What No One Will Tell You
10. To Go Further
11. Scientific Sources

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Key Takeaways

• Flat Nipple: does not protrude beyond the areola, may partially emerge with stimulation
• Inverted Nipple: retracts inwards, internal fibrosis
• Umbilicated Nipple: slightly indented in the center, between flat and inverted grade 1
• Grade 1: emerges easily — low impact on breastfeeding
• Grade 2: emerges but quickly reinverts — tools needed
• Grade 3: does not emerge — often requires surgery
• Breast pump from Day 1 in the maternity ward: essential

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Flat, inverted, umbilicated nipple: what's the difference?

These three terms describe distinct realities. Confusing them leads to incorrect assessments and inadequate care.

The flat nipple

A flat nipple does not, or barely, protrude beyond the surface of the areola, even without stimulation. It does not retract inwards: it is simply level with the skin, as if erased. With stimulation (cold, touch, breastfeeding), it may sometimes slightly protract, but this protrusion is minimal.

Caution: engorgement in the first few days can temporarily flatten a nipple that would normally protract well. This is not a permanently flat nipple – it's a transient situation related to tissue tension.

The inverted nipple

An inverted nipple is a nipple that retracts inwards into the breast. It does not protract spontaneously and may resist stimulation. The inversion is due to the retraction of fibrous tissue and/or shortened milk ducts that "pull" the nipple inwards. Research confirms: the higher the degree of fibrosis, the shorter and more tense the milk ducts, and the more difficult eversion is to achieve and maintain.

An inverted nipple can be unilateral or bilateral, congenital (present since puberty) or acquired (caused by surgery, mastitis, scar tissue).

The umbilicated nipple

A nipple whose center is slightly indented, like a belly button, appearing sunken rather than protruding. It falls between a flat nipple and a grade 1 inverted nipple: it does not fully emerge, but also does not retract deeply. It may respond to stimulation, partially emerge, then re-invert.

Prevalence

Approximately 10 to 20% of women have at least one flat or inverted nipple. One study cites 3.26% of young women with congenitally inverted nipples, with bilateral involvement in 86.8% of cases.

Sources: NCBI StatPearls, Inverted Nipple 2023; Aventus Clinic, Inverted Nipples 2026; Aeroflow Breastpumps, Flat or Inverted Nipples 2026

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Grades of inversion: from 1 to 3, what it changes

Grade 1 — Mild inversion

The nipple can be easily extracted by manual stimulation or cold. It protrudes well, maintains its position for a reasonable time, and gradually retracts afterwards. Impact on breastfeeding is generally limited. Simple techniques (stimulation before feeding, breast pump for a few seconds) are sufficient in most cases.

Surgical prognosis: 90-95% success with duct-preserving techniques.

Grade 2 — Moderate inversion

The nipple can be extracted, but it retracts quickly as soon as stimulation ceases. Moderate fibrosis. The milk ducts are retracted but not completely obstructed. Baby may have difficulty maintaining an effective latch as the nipple tends to reinvert during feeding.

Grade 3 — Severe inversion

The nipple cannot be extracted by manual stimulation. Significant fibrosis. The milk ducts are retracted, constricted, often very small in caliber. Impact on breastfeeding severely compromised, even impossible without surgical intervention.

Sources: NCBI StatPearls, Inverted Nipple. NIH/NCBI 2023; Go Mommy, Inverted Nipple Breastfeeding Shield: Grades & Latch Guide 2026; Willow Pump 2023

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What corrective surgery can — and cannot — do

Duct-preserving techniques

These techniques release the fibrous bands that hold the nipple inward while preserving the integrity of the milk ducts. Breastfeeding remains possible after the intervention — this is the priority for women of childbearing age.

Stevens et al. (Aesthetic Surgery Journal, 2019 — RCT 230 patients) emphasizes: "Correction of inverted nipple should attempt to preserve milk ducts in women of childbearing age."

Duct-dividing techniques

These techniques offer a more permanent correction for grade 3. They sacrifice some or all of the milk ducts. Breastfeeding on the operated side becomes very difficult, if not impossible.

Recurrence: a little-known fact

Even after successful surgical correction, partial reinversion is possible — especially under the influence of hormonal changes during pregnancy. Scar tissue and reconstructed ducts may not withstand the tension of breast changes. This is precisely what happened to me, and I discuss it in the next section.

Sources: Stevens et al. Aesthetic Surgery Journal. 2019. PubMed 29757354; StatPearls NCBI 2023; Motif Medical 2024

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My story: inverted nipples, surgery, piercing, and breast pump

I'm Roxane Bondu, founder of Lupa Allaitement. I have bilateral congenital inverted nipples. At 20, I had breast augmentation through the areola, and the surgeons took the opportunity to correct the inversion using a duct-preserving technique, to try and preserve my ducts and my future ability to breastfeed.

A few months after the operation, aware of the risk of the left nipple reinverting, I got a piercing to physically maintain eversion in the long term. A mechanical splint, so to speak.

More than ten years later, when I became pregnant, I removed the piercing during pregnancy. That's when the reality of the impact on the ducts became apparent: the piercing holes became connected to the milk ducts undergoing transformation. Result: milk partially leaks from the sides of the nipple. More difficult drainage, risk of stasis, sensation of partial flow.

→ Read our dedicated article: lupa-allaitement.fr/blog/piercing-mamelon-allaitement

At birth, my son was lethargic with jaundice. For a week in the hospital, ten professionals came and went without checking his suction. My nipples were shredded. Ill-fitting flanges were prescribed without actual measurement. An IBCLC finally misdiagnosed, in retrospect, a size of 27 mm. A substitute pediatrician finally saw the tongue tie.

After the frenotomy: the revelation. My son was finally nursing, but a long rehabilitation journey began.

With Simon, the co-parent, we started an 8-pump-a-day protocol. At 5 months, no more formula. At 6 months, my son was exclusively breastfed.

This is not a testimony to say that everyone can succeed under the same conditions. It's a testimony to say that information changes everything. If I had known, about my ducts, about my receptors, about my flange, about the tongue tie, I could have acted sooner, better, with less suffering.

It was from this experience that Lupa Allaitement was born. And Asymmetry.

→ Read also: lupa-allaitement.fr/blog/recepteurs-prolactine-72h-allaitement

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What it changes for nursing

A flat or inverted nipple does not deprive the baby of milk. It complicates the mechanics of latching.

For an effective latch, the nipple must reach the back of the baby's mouth against their soft palate. With a flat or inverted nipple, the baby doesn't have this anchor point. Their mouth "slips" on the areola. They may nurse superficially, which is recognizable by the "lipstick" shape of the nipple after feeding, without effectively transferring milk.

Associated risks:

• Poor milk transfer → baby not satiated despite long feeds
• Pain during feeding for the mother (superficial latch = friction)
• Slow establishment of lactation if stimulation is insufficient
• Pain during eversion in the first few days: adhesions gradually release. This is normal for the first 1 to 2 weeks — it's not a reason to stop

What improves over time

With frequent feedings or regular pumping, flat or inverted nipples tend to improve spontaneously. Adhesions loosen, and ducts gradually lengthen.

LLLI confirms: "Once the nipple can properly enter the baby's mouth, you should be able to breastfeed without discomfort."

Sources: La Leche League International, Inverted and Flat Nipples; Aeroflow Breastpumps 2026; Motif Medical 2025

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The breast pump: a tool for preparation and eversion before feeding

This is the main focus of this article and the least discussed.

The breast pump is not just a tool for collecting milk. For flat and inverted nipples, it is first and foremost an eversion tool to draw out the nipple and keep it extended just long enough for the baby to latch effectively.

Protocol: pumping before feeding baby

1. Before offering the breast, apply your flange and pump for 30 seconds to 2 minutes, depending on the degree of inversion.
2. Suction creates a vacuum that draws the nipple forward and keeps it extended.
3. Offer the breast to baby immediately after removing the flange, while the nipple is still everted.

This protocol is supported by NHS recommendations (first-line approach for flat or slightly inverted nipples) and Go Mommy (sources AAP, ABM, LLLI): 30 to 60 seconds of pumping before each feeding for grades 1 and 2.

Why it works

The breast pump's suction force does what fingers can't always do: it creates uniform negative pressure around the entire nipple, pulls the tissue forward without compressing it, and can gradually release adhesions that keep the nipple retracted. With regular use, many grade 1 and 2 inverted nipples eventually protract better and better, sometimes permanently.

Double benefit

This short pumping session before feeding does two things at once:

• It everts the nipple to facilitate the baby's latch.
• It can trigger the let-down reflex before the baby is at the breast — an immediate milk flow upon latch encourages the baby to continue.

The breast pump at the maternity ward: don't wait for it

Your breast pump should be with you at the maternity ward, from Day 1. If the baby can't latch, if the present professionals don't know what to do, your breast pump is there. You pump, you stimulate, you evert. You protect lactation while you work on the latch.

→ Read our full article: lupa-allaitement.fr/blog/recepteurs-prolactine-72h-allaitement

Sources: Go Mommy 2026; Boober IBCLC 2024; St. Louis Children's Hospital; Woven Lactation IBCLC 2025; Journal of Human Lactation

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How to measure your nipple when it is flat or inverted

The problem with flat measurement

Measuring a flat or inverted nipple at rest provides incomplete, or even false, information.

The solution: stimulate before measuring

• Stimulate your nipple manually: take it between thumb and forefinger, gently roll it to evert it.
• Or use your breast pump for a few seconds to draw it out.
• Measure the diameter at the base of the nipple as soon as it is extended — not at its tip, not in its retracted state.

Motif Medical (IBCLC Jacque Ordner): "Stimulate your nipples to evert them — this will help you distinguish the base of the nipple from the surrounding areola."

Beware of post-pumping

Post-pumping measurement is also not the correct reference: suction can swell the tissue. Measure at stimulated rest, with the nipple manually everted, not yet swollen by suction.

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Flange and non-protractile nipple: what you need to know

Size: rather smaller than normal

This is counter-intuitive but documented. A flange that is too large around a nipple that doesn't extend well primarily sucks in the areola and not the nipple itself. This is not effective, and can be painful. A well-fitted, or slightly smaller, flange concentrates suction on the nipple itself. It is this targeted suction that will gradually evert it.

Material: silicone primarily

For nipples that do not protract much or at all, soft silicone offers several advantages:

• It adheres to the skin and creates a gentle retaining effect on the areola, limiting excessive tissue suction into the tunnel.
• It is softer on a nipple undergoing eversion — the first few weeks can be uncomfortable.
• It adapts to the morphology by creating contact over the entire surface.

At Lupa Allaitement, flanges are available from 8 to 18 mm — designed in soft silicone with a suction cup effect, specifically adapted for small nipples and atypical morphologies.

Suction: start low

Resist the temptation to increase suction to "force" the nipple out. Too strong suction can be painful, create edema that complicates eversion, and traumatize delicate tissue. Start at the lowest pressure that generates visible movement in the tunnel. Increase gradually according to your comfort.

Sources: Motif Medical (IBCLC Jacque Ordner) 2024; MomMed 2024; Cleveland Clinic 2026; Lactation Loop IBCLC 2026

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What to do at the maternity ward — and what no one will tell you

Before birth

• Talk about your anatomy with your midwife and gynecologist now. Mention your grade if you know it.
• Consult an IBCLC prenatally — they can assess your nipple, anticipate difficulties, and prepare a starting plan for you.
• Prepare your breast pump before birth — check that your flanges are the correct size by manually stimulating your nipple to measure its base.

The first hours protocol

From Day 1, before each feeding:

1. Stimulate your nipple with your finger: take it between thumb and forefinger, gently roll for 30 to 60 seconds.
2. If manual stimulation is insufficient: apply your flange and pump for 30 seconds to 2 minutes in stimulation mode (high frequency, moderate pressure).
3. Offer the breast immediately once the nipple is everted — without waiting.
4. If baby doesn't latch despite eversion: pump for the full session. You are protecting your lactation. You are stimulating prolactin receptors. You are producing milk. This is what matters in these first 72 hours.

What you can observe with the breast pump

When your nipple starts to extend with the breast pump:

• The back-and-forth movement in the tunnel becomes more ample.
• Suction is better targeted at the nipple and less on the areola.
• The let-down reflex is triggered more easily.
• During subsequent feeds, the baby has more tissue to grasp.

Patience and regularity

The gradual eversion of an inverted nipple sometimes takes 1 to 2 weeks. This is normal. It is documented. Don't get discouraged too soon.

LLLI and La Leche League Canada are unanimous: "Most mothers with flat or inverted nipples can successfully breastfeed with patience, technique, and support."

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To go further

Everything related to the breast pump in difficult nipple situations: measurement, flange placement, reading movement in the tunnel, pre-feeding protocol is at the heart of the Madame Tire-Lait training.

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Summary

Definitions

• Flat nipple: does not extend past the areola, may partially extend with stimulation.
• Inverted nipple: retracts inward, internal fibrosis.
• Umbilicated nipple: slightly sunken in the center, between flat and inverted grade 1.

Grades

• Grade 1: extends easily, maintains eversion — low impact on breastfeeding.
• Grade 2: extends but quickly reinverts — moderate impact, tools needed.
• Grade 3: does not extend — severe impact, often surgery needed.

Breast pump before feeding

• 30 seconds to 2 minutes of pumping in stimulation mode before each feed.
• Offer breast immediately after.
• Triggers let-down reflex AND everts nipple: double benefit.

Measurement

• Measure after manual stimulation (not flat, not after pumping).
• Measure the base of the everted nipple.

Flange

• Slightly smaller than normal to concentrate suction on the nipple.
• Soft silicone preferred: less friction, better morphological adaptation.
• Suction: start low, increase gradually.

At the maternity ward

• Breast pump present from Day 1 — not in a box at home.
• Manual stimulation + pumping before each feed.
• Consult an IBCLC as soon as possible if latching is difficult.

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Related articles on lupa-allaitement.fr

• Elastic nipple and breast pump: diagnosis and suitable flange
• Prolactin receptors and the 72-hour window
• Nipple piercing and breastfeeding

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Sources: [1] NCBI StatPearls. Inverted Nipple. 2023. ncbi.nlm.nih.gov/books/NBK563190/ — [2] Stevens WG et al. Aesthetic Surgery Journal. 2019. PubMed 29757354 — [3] Commentary Aesthetic Surgery Journal. 2019. academic.oup.com/asj/article/39/6/NP176/5421045 — [4] Aeroflow Breastpumps. 2026. — [5] Motif Medical, IBCLC Jacque Ordner. 2024. — [6] Go Mommy. Inverted Nipple Breastfeeding Shield. 2026. — [7] La Leche League International. llli.org — [8] La Leche League Canada. lllc.ca — [9] Boober IBCLC. 2024. — [10] MomMed. 2024. — [11] Aventus Clinic. 2026.