Caput vs Moulding: How Your Baby’s Head Changes Shape During Labour

During labour, your baby’s head may swell, elongate, or look uneven at birth. This can be surprising, even alarming, if you’re not expecting it. Two normal processes explain most of these changes: caput succedaneum and moulding. While they often occur together, they are not the same thing. Understanding how and why your baby’s head changes shape during labour helps you distinguish normal adaptation from signs that need medical attention.

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Labour is not a gentle journey for your baby. As contractions push your baby through the birth canal, their head must adapt to tight spaces, changing pressures, and the unique shape of your pelvis. Unlike an adult skull, a newborn’s head is designed to be flexible. This flexibility allows the baby to be born vaginally, but it can temporarily alter the head's appearance.
Parents are often told, “Don’t worry, the head will round out.” While reassuring, this explanation skips the fascinating physiology behind how and why those changes happen. The two main contributors are caput and moulding, terms that sound similar but describe very different processes.

Why a Baby’s Head Can Change Shape During Labour

A newborn’s skull is made up of several bony plates joined by soft connective tissue called sutures and fontanelles. This design allows:

  • Overlapping of skull bones under pressure
  • Temporary reshaping without injury
  • Protection of the brain while allowing flexibility
As the baby’s head presses against the cervix, pelvic bones, and vaginal walls, it encounters resistance. The response to that resistance depends on where the pressure occurs and how long it lasts, which is what separates caput from moulding.

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What Is Caput Succedaneum

Caput succedaneum refers to soft tissue swelling of the scalp, caused by pressure on the baby’s head during labour. This swelling develops above the skull bones, in the skin and subcutaneous tissue.

What Causes Caput

  • Prolonged pressure of the baby’s head against the cervix
  • Early rupture of membranes, which removes the cushioning effect of amniotic fluid
  • Long labours or slow descent
  • Assisted vaginal deliveries (vacuum or forceps)
Fluid collects in the scalp tissue due to impaired venous and lymphatic drainage while the head is compressed.

How Caput Looks and Feels

  • Soft, puffy swelling on the scalp
  • Often crosses suture lines
  • May feel squishy or fluid-filled
  • Usually visible immediately at birth
Caput is often most noticeable on the part of the head that presented first during labour.

Is Caput Dangerous

Caput is benign and temporary. It does not involve bleeding, brain injury, or skull damage. In most cases:

  • Swelling reduces within 24–72 hours
  • No treatment is required
  • The scalp returns to its normal shape on its own

What Is Moulding

Moulding refers to the overlapping or shifting of the skull bones themselves as the baby passes through the birth canal. This is a structural adjustment, not a fluid swelling.

What Causes Moulding

  • Strong uterine contractions
  • Tight pelvic fit
  • Long or obstructed labour
  • First vaginal births, where tissues are less stretched
Under sustained pressure, the skull bones slide over one another at the sutures, allowing the head to become narrower or elongated.

How Moulding Looks and Feels

  • Elongated or cone-shaped head
  • Ridge-like edges where bones overlap
  • Firmer than caput
  • Does not cross suture lines
Moulding may not be immediately obvious, but it becomes clearer as caput swelling reduces.

Is Moulding Dangerous

Physiological moulding is normal and protective.

  • It reduces the head diameter during birth
  • It does not damage the brain
  • Skull bones gradually realign within days to weeks
In most babies, the head shape normalises completely within 1–2 weeks.

Caput vs Moulding: Key Differences

Here are the key differences between caput and moulding:

Feature

Caput Succedaneum

Moulding

Affects

Scalp soft tissue

Skull bones

Cause

Fluid accumulation

Bone overlap

Texture

Soft, puffy

Firm, ridged

Crosses sutures

Yes

No

Timing

Present at birth

It may become clearer after birth

Resolution

1–3 days

Days to weeks

Risk

Benign

Benign when physiological


Many babies have both caput and moulding, fluid swelling on top of reshaped bones.

Why These Changes Are More Common in Some Births

Certain labour situations increase pressure on the baby’s head:

  • First vaginal births, where descent takes longer
  • Prolonged second stage of labour
  • Early rupture of membranes
  • Induced or augmented labour, which can intensify contractions
  • Assisted deliveries, especially vacuum extraction
These factors increase the duration, intensity, or both of pressure.

How Doctors Assess Head Changes at Birth

Immediately after birth, doctors examine the baby’s head to determine whether swelling is benign or needs monitoring. They check:

  • Texture and firmness
  • Whether swelling crosses sutures
  • Presence of bruising
  • Baby’s neurological status
Caput and moulding are diagnosed clinically and usually require no imaging or intervention.

Conditions That Can Look Similar But Are Different

It’s important to distinguish caput and moulding from less common conditions.

Cephalohematoma

  • Bleeding under the periosteum
  • Does not cross sutures
  • Feels firm and well-defined
  • Resolves over weeks
  • Slightly higher risk of jaundice
Unlike caput, cephalohematoma involves blood, not fluid.

Subgaleal Haemorrhage

  • Rare but serious
  • Extensive bleeding under the scalp
  • Rapidly increasing head size
  • Requires urgent care
This is usually associated with vacuum deliveries and is carefully monitored in hospital settings.

What Parents Often Worry About and Why They Shouldn’t

It’s common to worry that an oddly shaped head means brain injury or permanent deformity. In reality:

  • The brain is well protected inside flexible bones
  • Caput and moulding do not affect intelligence or development
  • Head shape almost always normalises without intervention
Paediatricians monitor head circumference and skull symmetry during routine newborn checkups.

How Long Does It Take for the Head to Look “Normal”

  • Caput: noticeable improvement in 24–48 hours
  • Moulding: gradual rounding over 1–2 weeks
  • Full normalisation: may take up to 6 weeks in some babies
Gentle handling and normal positioning are sufficient. Special pillows or shaping devices are not required.

Does Head Shape Affect Breastfeeding or Comfort

Occasionally, babies with significant moulding may:

  • Prefer turning their head to one side
  • Be slightly uncomfortable in certain positions
Skin-to-skin contact and varied breastfeeding positions usually resolve this naturally.

When Should You Ask the Doctor Again

While caput and moulding are normal, follow up if you notice:
  • Swelling increases after birth
  • Redness, warmth, or signs of infection
  • Poor feeding or unusual lethargy
  • Head shape has not improved after several weeks
These are rare but worth checking.

Emotional Context for Parents

Seeing your newborn’s head look swollen or misshapen can be unsettling, especially if you were not warned.

Understanding that this is evidence of adaptation, not injury, often brings relief. Your baby’s head changed shape not because something went wrong, but because their body did exactly what it was designed to do.

Caput and moulding are not signs of trauma; they are signs of successful adaptation. As your baby navigates the narrow passage of birth, their head changes shape to protect the brain and allow safe delivery.

What looks unfamiliar in the first hours of life is usually temporary, harmless, and remarkably efficient biology at work. Within days to weeks, your baby’s head will settle into the round shape you expect, carrying no memory of the pressure it once endured.

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FAQs on Caput vs Moulding: How Your Baby’s Head Changes Shape During Labour


  1. Can caput or moulding cause long-term head shape problems?
    No. Both resolve naturally without affecting skull growth or brain development.
  2. Is moulding more common in long labours?
    The longer the pressure, the more opportunity for skull bones to overlap.
  3. Can a C-section baby have caput?
    Caput can develop before surgery if labour progresses before the C-section.
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