OBJECTIVE: Ankyloglossia is a congenital condition characterized by an abnormally short, thickened, or tight lingual frenulum that restricts tongue mobility. The objective of this study was to systematically review literature on surgical and nonsurgical treatments for infants with ankyloglossia.METHODS: Medline, PsycINFO, Cumulative Index of Nursing and Allied Health Literature, and Embase were searched up to August 2014. Two reviewers independently assessed studies against predetermined inclusion/exclusion criteria. Two reviewers independently extracted data regarding participant and intervention characteristics and outcomes and assigned quality and strength-of-evidence ratings.RESULTS: Twenty-nine studies reported breastfeeding effectiveness outcomes (5 randomized controlled trials [RCTs], 1 retrospective cohort, and 23 case series). Four RCTs reported improvements in breastfeeding efficacy by using either maternally reported or observer ratings, whereas 2 RCTs found no improvement with observer ratings. Although mothers consistently reported improved effectiveness after frenotomy, outcome measures were heterogeneous and short-term. Based on current literature, the strength of the evidence (confidence in the estimate of effect) for this issue is low. We included comparative studies published in English. The evidence base is limited, consisting of small studies, short-term outcomes, and little information to characterize participants adequately. No studies addressed nonsurgical interventions, longerterm breastfeeding or growth outcomes, or surgical intervention compared with other approaches to improve breastfeeding, such as lactation consultation.CONCLUSIONS: A small body of evidence suggests that frenotomy may be associated with motherreported improvements in breastfeeding, and potentially in nipple pain, but with small, shortterm studies with inconsistent methodology, strength of the evidence is low to insufficient. Dr Francis conceptualized and designed the study, and drafted the initial manuscript; Dr McPheeters conceptualized and designed the study, carried out the initial analyses, and reviewed and revised the manuscript; Dr Krishnaswami carried out the initial analyses, and reviewed and revised the manuscript; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work. Despite these studies, consensus on the role of ankyloglossia in breastfeeding difficulties is lacking. A minority of surveyed pediatricians (10%) and otolaryngologists (30%) believe ankyloglossia commonly affects feeding, whereas 69% of lactation consultants feel that it frequently causes breastfeeding problems. 3 Therefore, depending on the audience, enthusiasm for its treatment varies. Currently, the National Health Service and the Canadian Pediatric Society recommend treatment if ankyloglossia interferes with breastfeeding. 4 However, a standard definition of "interference" with breastfeeding is not provided, leaving room for interpretation and variation in treatment thr...