Background: breastfeeding optimises health outcomes for both mothers and infants. Although most women want to breastfeed, they report commencing infant formula because of nipple pain, unsettled infant behaviour, and infant growth concerns. To date, existing approaches to fit and hold (‘latch and positioning’) have been demonstrated not to help breastfeeding outcomes, and women report widespread dissatisfaction with the quality of support and conflicting advice they receive. Breast and nipple pain, difficulty with latching and sucking, fussing at the breast, back-arching, marathon feeds, excessively frequent feeds, poor weight gain, breast refusal, and crying due to poor satiety often signal suboptimal positional instability and impaired milk transfer, but may be misdiagnosed as medical conditions. Over the past two decades, there has been an exponential increase in numbers of infants being treated with medications, laser or scissors frenotomy, and manual therapy for unsettled behaviour and breastfeeding difficulty. New approaches to clinical breastfeeding support are urgently required. Method and results: we analyse the findings of a literature search of PubMed and MEDLINE databases for ultrasound studies measuring sucking in term and preterm infants. The findings demonstrate that the Stripping Action Model of infant suck during breastfeeding, and the resultant Structural Model of infant suck dysfunction, are inaccurate. Instead, ultrasound data demonstrates the critical role of intra-oral vacuum for milk transfer. We integrate these two-dimensional ultrasound results with clinical experience of the third dimension, volume, to propose a Gestalt Model of the biomechanics of healthy infant suck during breastfeeding. The Gestalt Model hypothesises that optimal intra-oral vacuums and breast tissue volumes are achieved when mother-infant positional stability eliminates conflicting intra-oral vectors, resulting in pain-free, effective milk transfer. Conclusion: the Gestalt Model of the biomechanics of healthy infant suck during breastfeeding opens up the possibility of a new clinical method which may prevent unnecessary medical treatments for breastfeeding problems and related unsettled infant behaviour in early life.