Biomechanics of milk extraction during breast-feeding

Abstract

How do infants extract milk during breast-feeding? We have resolved a century-long scientific controversy, whether it is sucking of the milk by subatmospheric pressure or mouthing of the nippleareola complex to induce a peristaltic-like extraction mechanism. 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. The physical mechanisms executed by the infant have been intriguing topics. We used an objective and dynamic analysis of ultrasound (US) movie clips acquired during breast-feeding to explore the tongue dynamic characteristics. Then, we developed a new 3D biophysical model of the breast and lactiferous tubes that enables the mimicking of dynamic characteristics observed in US imaging during breastfeeding, and thereby, exploration of the biomechanical aspects of breast-feeding. We have shown, for the first time to our knowledge, that latch-on to draw the nipple-areola complex into the infant mouth, as well as milk extraction during breast-feeding, require development of time-varying subatmospheric pressures within the infant's oral cavity. Analysis of the US movies clearly demonstrated that tongue motility during breast-feeding was fairly periodic. The anterior tongue, which is wedged between the nipple-areola complex and the lower lips, moves as a rigid body with the cycling motion of the mandible, while the posterior section of the tongue undulates in a pattern similar to a propagating peristaltic wave, which is essential for swallowing.submental ultrasound | sucking pressure | computational model | fluid-structure interaction B reast-feeding is strongly publicized and encouraged by many societies and communities. It is well accepted that breast milk provides the infant both nutrients and immunities required for growth and development during the first months after birth. It is less known that breast-fed infants exercise and prepare their orofacial muscles for future tasks of speaking and chewing (1), and also have higher oxygen saturation than bottle-fed infants (2). Breast-feeding is the outcome of a dynamic synchronization between oscillation of the infant's mandible, rhythmic motility of the tongue, and the breast milk ejection reflex that drives maternal milk toward the nipple outlet. First, the infant latches onto the breast and nipple so that the nipple, areola, and underlying mammary tissue and lactiferous ducts are drawn into the infant's mouth with the nipple tip extended as far as the hard-soft palate junction (HSPJ). Then, the infant moves its mandible up and down, compressing the areola and the underlying lactiferous ducts with its gums in a suckling process that extracts the milk into its mouth (3, 4). Simultaneous with compression, spontaneous undulating motions of the infant tongue channel the milk posteriorly and trigger the swallowing reflex (5). During breast-feeding, suckling, swallowing, and breathing are coordinated by the central nervous system in a way that allows for...

Breastfeeding improvement following tongue‐tie and lip‐tie release: A prospective cohort study

“…The data in this study demonstrate a significant increase in milk transfer rate (∼155% improvement). With improved mobility of the midtongue toward the palate, infants can improve seal and vacuum production, leading to more efficient milk transfer . Furthermore, the authors have noticed improved stamina on the breast; when the tongue motion drives milk extraction rather than compensatory muscle movements, the baby does not fatigue.…”

Oral dysfunction as a cause of malocclusion

“…Breastfeeding is the first and perhaps most critical experience to facial development. Unlike with bottle feeding, infants draw the breast deep into the mouth and the breast expands and shapes the hard palate through repeated pressure and peristaltic wave . Breastfeeding requires jaw compression, which helps develop better masseter muscles than does bottle feeding …”

“…Unlike with bottle feeding, infants draw the breast deep into the mouth and the breast expands and shapes the hard palate through repeated pressure and peristaltic wave. 7 Breastfeeding requires jaw compression, which helps develop better masseter muscles than does bottle feeding. 8 Children exclusively breastfed appeared to have a lower incidence of malocclusion later in life when compared to bottle-fed babies.…”

Trauma Mamilar: Cuidados Adotados por Mulheres no Pós-parto

“…A sucção do bebê e os movimentos de mandíbula, língua e lábios realizados ao longo das frequentes mamadas promovem movimento, compressão e extensão mamilar 12 . Esse processo pode ocasionar dor e dano ao tecido e, quando a pega está incorreta, há maior força de pressão intraoral do bebê, ocasionando numa maior extensão do tecido mamilar 22 .…”