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The structures and functions of a newborn baby’s and young infant’s mouth can affect the life-long processes of feeding and speech. While many parents (and professionals) may be unaware, problems can begin to arise in utero and in the first weeks to months of life. However, through parent and professional education, there are ways to keep a baby’s mouth development “on track” beginning at birth. This article describes and discusses face, mouth, and throat characteristics in newborn and young babies, so parents and professionals can identify typical vs. atypical anatomy and physiology.

Face, Mouth, and Throat Characteristics in Newborns and Early Infancy

Newborns, children, and adults share some similar facial characteristics if their structures have developed appropriately. This includes a nice broad horizontal eye area (approximately the width of one eye times 5), the center corners of the eyes lining up with the widest part of the nose, a relatively straight lip line, and a nose to philtrum angle that is 90 to 110 degrees (Boshart, 1999).

However, newborns have eleven unique mouth and throat characteristics that warrant discussion.

A newborn has:

  • Mouth and throat structures in very close proximity
  • Limited open space within the mouth and throat areas
  • A small, slightly retruded (pulled back) lower jaw
  • A wide “U” shaped palate
  • A flexible/moveable palate
  • Nose breathing
  • A tongue that fills the mouth at rest
  • A deeply cupped tongue when suckling
  • Gums that enlarge to assist with the latch
  • Ample sucking pads in the cheeks
  • Relatively horizontal positioning of the Eustachian tubes

(Bahr, 2001, 2010, 2015; Coryllos, Genna, & Salloum, n.d.; Geddes, Kent, Mitoulas, & Hartmann, 2008; Morris, 1985; Morris & Klein, 2000; Oetter, Richter, & Frick, 1995; Page, 2003b; Upledger & Vredevoogd, 1983; Upledger, 1996)

Mouth and Throat Structures Close/Limited Space

A newborn’s mouth and throat structures are close together, so there is limited open space within the mouth and throat areas. This helps typically developing, full-term newborns to safely feed and swallow. As the infant grows and develops feeding skills, there is increasing open space within the infant’s mouth and throat areas. Therefore, the mouth and throat areas of a newborn are different from a three or six- month old baby secondary to growth. Feeding therapists (e.g., lactation consultants, speech-language pathologists, occupational therapists, orofacial myofunctional therapists, etc.) must keep these changes in mind when helping parents develop feeding programs.

Retruded Lower Jaw

Newborn babies have small, slightly retruded (pulled back) lower jaws (mandibles) which are approximately 30 percent of adult size at birth (Page, 2003a). There is significant jaw growth in the first year of life (Enlow, 1982; Page, 2003b; Van der Liden, 1986). By six months parents will notice their baby’s lower jaw beginning to line up with the baby’s philtrum (area above the upper lip) and bridge of the nose when viewed from the side (i.e., profile). Jaw growth is facilitated via appropriate feeding and mouth development activities (e.g., breastfeeding; age appropriate food and liquid introduction, appropriate mouthing of hands, fingers, and mouth toys; etc.).

“U”: Shaped Palate

The newborn’s palate (roof of the mouth) has a wide “U” shape and is approximately ¾ to 1 inch wide (Page, 2003b) from side-to-side across midline (i.e., 50 percent of adult width). The palate is flexible and moveable at birth but will harden over time. Palatal development and shape are significantly influenced by the placement of the baby’s tongue at rest and during breastfeeding. The baby’s tongue should rest lightly suctioned against the roof of the mouth, and the mother’s breast should be drawn deeply into the baby’s mouth during breastfeeding to help maintain the palate’s broad “U” shape (Page, 1999).

Flexible Palate

However, if a baby has an open-mouth posture at rest or uses a pacifier excessively, the baby’s tongue cannot do its job in keeping the palate’s shape. Additionally, bottle feeding is a very different process than breastfeeding and does not help to maintain the palate’s shape (Gomes, Trezza, Murade, & Padovani, 2006; Jacinto-Goncalves, Gaviao, Berzin, de Oliveira, & Semeguini, 2004). Bottle feeding is a medicalized way of feeding a human infant. According to the American Academy of Pediatrics (2012, p. e827), “breastfeeding and human milk are the normative standards for infant feeding and nutrition.”

Nose Breathing

If the palate’s shape becomes high and narrow, this will impact the shape and size of the nasal area as the palate is the floor of the nasal cavity. Small nasal areas can make nose breathing difficult and nasal passages hard to clear leading to upper respiratory issues. Nose breathing is needed for effective suck-swallow-breathe synchrony used in breast and bottle feeding as well as efficient oxygenation of the blood for all life processes (Alexander, 1987; Gray, 1980; Lundberg, Farkas-Szallasi, Weitzberg, Rinder, Lidholm, Anggaard, Hokfelt, Lundberg, & Alving, 1995; McCann, Licinio, Wong, Yu, Karanth, & Rettorri, 1998; Northrup, 2001, 2005; Page, 2003a & b; Schedin, Norman, Gustafsson, Herin, & Frostell, 1996).

Tongue Fills the Mouth at Rest

As previously mentioned, the newborn’s tongue fills the mouth at rest to help maintain the palate’s broad shape. The tongue should be mobile and not tied nor restricted. Tongue and other oral restrictions may be genetic (Acevedo, da Fonseca, Grinham, Doudney, Gomes, de Paula, & Stanier, 2010; Han, Kim, Choi, Lim, & Han, 2012; Klockars & Pitkaranta, 2009). Clinically, it seems that babies with tongue ties may also have lip or buccal (cheek) ties. These ties are currently referred to as tethered oral tissues.

Tongue tie (i.e., ankyloglossia frequently caused by a short, thick lingual frenum) usually restricts the tongue from coming over the lower gum during suckling. This can significantly impact feeding and may cause the baby to use compensatory, abnormal tongue and jaw movements during breast or bottle feeding such as tongue humping, bunching, and/or thrusting as well as chomping on the breast or bottle for stability. (Geddes, Langton, Gollow, Jacobs, Hartmann, and Simmer, 2008; Haham, Marom, Mangel, Botzer, & Dollberg, 2014). Lip and/or cheek ties may affect a baby’s latch as lips and cheeks work together for a symmetrical lip latch on the breast or bottle (Kotlow, 2013). The degree of tongue, lip, or cheek tethering determines their impact on feeding and whether a release or revision is needed.

Deeply Cupped Tongue

A newborn’s tongue is deeply cupped during reflexive suckling (a response with which typical babies are born). During suckling, the tongue has a “distinctive, rhythmical, backward-forward stripping movement that helps draw liquid into the mouth” (Morris & Klein, 2000, p. 77). “Breast-feeding is a dynamic process, which requires coupling between periodic motions of the infant’s jaws, undulation of the tongue, and the breast milk ejection reflex” (Elad, Kozlovsky, Blum, Laine, Po, Botzer, Dollberg, Zelicovish, & Sira, 2014, p. 5230). While the movements for breast and bottle feeding appear similar, there are differences between these processes.

Enlarged Gums

During the feeding process, the newborn’s gums reportedly enlarge to assist with the latch (Montagu, 1986). This enlargement (which is likely due to increased blood supply to the area) reportedly subsides between 3 and 6 months of age as the baby uses a volitional 3-dimentional suck in place of the reflexive suckle. In the 3-dimentional suck, the tip and sides of the tongue move upward and the lips pucker. The tongue is still cupped but not as deeply cupped as that of the newborn. Tongue cupping and tongue tip elevation are essential for the development of a mature swallowing pattern.

Buccal Sucking Pads

Full-term typically developing newborns are also born with buccal fat pads (commonly called sucking pads). These develop toward the end of pregnancy when other fat is developing on a baby’s body, so premature babies do not develop them and near-term babies may have thin ones. Sucking pads are balls of fat in a baby’s cheeks that help keep the cheeks against the gums, so the baby can attain appropriate intraoral pressure during feeding. They supply lateral stability in the mouth until the baby’s cheek muscles (particularly the buccinators) gain control of the process between 4 and 6 months. At this time, the baby engages the 3-dimentional suck and chews on appropriate mouth toys and safe first foods while the sucking pads shrink and the cheek muscles become increasingly active.

Horizontal Eustachian Tubes

The Eustachian tubes (which originate at the back of the nasopharynx and end in the middle ear space) are relatively horizontal in newborns. This is one reason babies’ bodies are positioned at a 45 degree (or greater) angle when bottle fed. If a baby is bottle fed lying down (supine), there is greater opportunity for liquid to enter the Eustachian tubes than if a baby is feed upright (NIH, 2014). Bottle feeding also seems to involve a different set of pressures than breastfeeding. In breastfeeding, the pressures in the oral, nasal, and pharyngeal systems seem to be equalized. Breastmilk also reportedly contains some antibacterial qualities that will likely protect the baby if breastmilk should enter the Eustachian tubes. Therefore, a variety of breastfeeding positions may be safely used to feed a baby. It is also well-known that breastfed babies have fewer middle ear problems and upper respiratory issues than bottle fed babies (Aniansson, Alm, Andersson, Hakansson, Larsson, Nylen, Peterson, Rigner, Svanborg, Sabharwal, et al., 1994; Watkins, Leeder, & Corkhill, 1979).

Conclusion

It is important that parents and professionals have a good understanding of newborn and early infant anatomy, physiology, growth, and development, so they can apply and encourage the best possible mouth, feeding, and vocal development practices in babies and young children. In this article, we touched on newborn and early infant anatomy and physiology. However, the processes of feeding, oral play, and early vocal/speech development are overlaid on this anatomy and physiology, and these processes develop significantly during the first two years of life beginning at birth. Information on feeding, mouth development activities, and early speech development can be found in books by Morris & Klein (2000), Bahr (2010), and others. To date, there appears to be only one longitudinal study on feeding and pre-speech skills by Morris (1978, revised 2003). Therefore, research is required.

Links of Interest

  1. Nobody Ever Told Me (or my Mother) That!: Everything from Bottles and Breathing to Healthy Speech Development
  2. Oral Motor Assessment and Treatment: Ages and Stages
  3. For more information, visit her website: www.agesandstages.net 

References

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  2. Alexander, R. (1987). Oral-motor treatment for infants and young children with cerebral palsy. Seminars in Speech and Language 8(1), 87-100.
  3. American Academy of Pediatrics. (2010). Breastfeeding and the use of human milk. Pediatrics, 129(3), E827-e841.
  4. Aniansson, G., Alm, B., Andersson, B., Hakansson, A., Larsson, P., Nylen, O., Peterson, H., Rigner, P., Svanborg, M., Sabharwal, H., et al. (1994). A prospective cohort study on breast-feeding and otitis media in Swedish infants. The Pediatric Infectious Disease Journal, 13(3), 183-188.
  5. Bahr, D. (2015). Everything you need to know about a baby’s mouth for good feeding, speech, and mouth development. Las Vegas, NV: Ages and Stages® E-Course.
  6. Bahr, D. (2010). Nobody ever told me (or my mother) that! Everything from bottles and breathing to healthy speech development. Arlington, TX: Sensory World.
  7. Bahr, D. C. (2001). Oral motor assessment and treatment: Ages and stages. Needham Heights, MA: Allyn & Bacon.
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