The Relationship between Feeding and Non-Nutritive Sucking Behaviours and Speech Sound Development: A Systematic Review

<b><i>Background:</i></b> Children with and without speech sound disorders (SSDs) are exposed to different patterns of infant feeding (breast/bottle-feeding) and may or may not engage in non-nutritive sucking (NNS) (pacifier/digit-sucking). Sucking and speech use similar oral musculature and structures, therefore it is possible that early sucking patterns may impact early speech sound development. The objective of this review is to synthesise the current evidence on the influence of feeding and NNS on the speech sound development of healthy full-term children. <b><i>Summary:</i></b> Electronic databases (PubMed, NHS CRD, EMBASE, MEDLINE) were searched using terms specific to feeding, NNS and speech sound development. All methodologies were considered. Studies were assessed for inclusion and quality by 2 reviewers. Of 1,031 initial results, 751 records were screened, and 5 primary studies were assessed for eligibility, 4 of which were included in the review. Evidence from the available literature on the relationship between feeding, NNS and speech sound development was inconsistent and inconclusive. An association between NNS duration and SSDs was the most consistent finding, reported by 3 of the 4 studies. Quality appraisal was carried out using the Appraisal Tool for Cross-Sectional Studies (AXIS). The included studies were found to be of moderate quality. <b><i>Key Messages:</i></b> This review found there is currently limited evidence on the relationship between feeding, NNS and speech sound development. Exploring this unclear relationship is important because of the overlapping physical mechanisms for feeding, NNS and speech production, and therefore the possibility that feeding and/or sucking behaviours may have the potential to impact on speech sound development. Further high-quality research into specific types of SSD using coherent clinically relevant assessment measures is needed to clarify the nature of the association between feeding, NNS and speech sound development, in order to inform and support families and health care professionals.