Highlights
In a nationwide Danish cohort of 656,240 infants born from 2014 through 2024, 56,737 infants, or 8.6%, underwent frenotomy within the first year of life.
Annual frenotomy incidence more than doubled, rising from 5.3 per 100 infants in 2015 to 12.1 per 100 infants in 2024, with consistently higher rates in male infants.
Practice patterns varied strikingly across municipalities, with 2024 cumulative incidence ranging from 4.2 to 36.1 per 100 infants, suggesting substantial differences in diagnostic thresholds, referral pathways, or local practice culture.
Severe complications were rare, but bleeding was more frequent after frenotomy than in matched controls, repeat procedures occurred in 6.3%, and hospital contacts for feeding difficulty or poor weight gain were more common among infants who underwent the procedure.
Background
Frenotomy, the incision of a restrictive lingual frenulum, is increasingly performed in early infancy for suspected ankyloglossia, commonly referred to as tongue-tie. The rationale is that impaired tongue mobility may contribute to poor latch, maternal nipple pain, suboptimal milk transfer, prolonged feeds, and concerns about infant weight gain. In practice, however, diagnosis is often imprecise, thresholds for intervention vary considerably, and the relationship between visible frenulum anatomy and clinically meaningful breastfeeding dysfunction is not straightforward.
This mismatch between procedural growth and evidentiary certainty has become a major clinical issue. Although frenotomy is generally viewed as a minor office-based intervention, it is being applied at scale in otherwise healthy newborns and young infants. When procedure rates rise rapidly in a universal health system, clinicians and policymakers must ask whether this reflects improved recognition of a meaningful condition, overdiagnosis of normal variation, therapeutic enthusiasm in advance of evidence, or some combination of these factors.
The Danish study by Sonne and colleagues is therefore important not simply because it quantifies use, but because it examines time trends, demographic patterns, geographic variation, and selected downstream outcomes in a whole-country birth cohort. In doing so, it provides a population-level view of how frenotomy is being integrated into infant care in the real world.
Study Design and Methods
Design and data sources
This was a nationwide cohort study conducted within Denmark’s universal health care system. The investigators included all infants born in Denmark between January 1, 2014, and December 31, 2024, using individual-level linkage across the Danish National Health Service Register and the National Patient Registry. These linked administrative data allowed near-complete follow-up for procedural coding, hospital contacts, and selected adverse events.
Population and exposure
The study population comprised 656,240 infants, of whom 337,110, or 51.4%, were male. Frenotomy procedures were identified through procedure codes, and infants who underwent frenotomy were analyzed for incidence patterns and postprocedure outcomes. For comparative analyses of complications and health care use, matched controls without frenotomy were identified in a 1:5 ratio.
Outcomes
The main measures included annual incidence and age-specific incidence of frenotomy, cumulative incidence by birth cohort, birth order, and geographic area, including regional and municipal estimates. The investigators also evaluated selected complications and related events, focusing on bleeding within 30 days, repeat procedures, and hospital contacts related to feeding difficulties or failure to thrive.
Why this design matters
The strengths of this design are scale, completeness, and external validity within the Danish setting. The study captures ordinary clinical practice rather than referral-center behavior, and the geographic analysis is particularly informative for a procedure whose indication is often clinically subjective. At the same time, registry-based work cannot fully establish indication quality, breastfeeding severity, diagnostic criteria for ankyloglossia, or whether the infants selected for frenotomy differed systematically from controls in ways not captured by matching.
Key Findings
Procedure rates increased sharply over time
Among all infants in the cohort, 56,737 underwent frenotomy during the first year of life, corresponding to 8.6% of Danish infants born during the study period. The annual incidence rose from 5.3 per 100 infants in 2015 to 12.1 per 100 infants in 2024. This pattern indicates more than a doubling of use over less than a decade.
The magnitude of increase is clinically striking. A procedure once reserved for a relatively limited subset of infants appears to have become common in routine newborn care. By 2024, roughly 1 in 8 infants underwent frenotomy within the first year of life. That level of penetration would normally be expected only for interventions with broad consensus regarding indications and benefit, which is not currently the case for infant tongue-tie management.
Frenotomy was performed very early in life
The median age at frenotomy was 2 weeks, with an interquartile range of 0 to 5 weeks. This timing fits the clinical scenario in which breastfeeding concerns emerge soon after birth and intervention is pursued rapidly, often before sustained lactation support or natural feeding adaptation has occurred. Early timing may reflect the understandable urgency surrounding infant feeding difficulties, but it also underscores the need for careful diagnostic evaluation, because newborn feeding problems are multifactorial and frequently improve with skilled lactation support.
Male infants had higher incidence than female infants
Incidence was consistently higher in male infants throughout the study period. In 2024, annual incidence was 14.1 per 100 male infants compared with 10.0 per 100 female infants. This sex difference is consistent with prior reports suggesting that clinically recognized ankyloglossia is more common in males, although it remains uncertain how much of this reflects biological predisposition versus ascertainment patterns or procedural thresholds.
Cumulative incidence rose across birth cohorts
The cumulative incidence increased from 4.5 per 100 infants in the 2014 to 2017 birth cohort to 12.0 per 100 infants in the 2021 to 2024 cohort. This reinforces that the observed trend is not a short-term fluctuation but a sustained shift in practice over multiple birth cohorts.
Most procedures occurred in private practice and were performed by otolaryngologists
The overwhelming majority of procedures were performed in private practice settings, accounting for 51,746 of 56,737 procedures, or 91.2%. Otolaryngologists performed 52,380 procedures, or 92.3% of the total. These findings indicate that frenotomy in Denmark is predominantly an ambulatory specialist procedure rather than a hospital-based intervention. That distribution may have implications for access, documentation, thresholds for intervention, and the consistency of multidisciplinary feeding assessment before surgery.
Geographic variation was substantial
One of the most policy-relevant findings was the degree of geographic variation. Municipal cumulative incidence in 2024 ranged from 4.2 per 100 infants to 36.1 per 100 infants. Variation of this magnitude is difficult to explain by biology alone. It more likely points to differences in local professional norms, parental expectations, referral behavior, lactation support availability, coding practice, or the influence of high-volume procedural communities.
In health services research, wide small-area variation often signals uncertainty in indications. When clinicians face a condition with no single objective diagnostic threshold and incomplete evidence for benefit, care may become highly dependent on local culture rather than patient need alone. Frenotomy appears to fit that pattern.
Severe complications were rare, but not absent
Bleeding within 30 days of the procedure was uncommon overall but occurred more often among infants who underwent frenotomy than among matched controls: 11 of 56,737 infants, or 0.02%, versus 13 of 274,476 controls, or 0.005%. The reported risk ratio was 4.1, with a 95% confidence interval of 1.9 to 9.3. This means the absolute risk was very low, but the relative increase was measurable and statistically significant.
For clinicians counseling families, both dimensions matter. The low absolute event rate supports the view that severe bleeding is rare. At the same time, the procedure is not entirely risk-free, and population-level expansion of a procedure with modest or uncertain benefit can still generate avoidable harm when applied to large numbers of infants.
Repeat procedures were not uncommon
Repeat frenotomy was performed in 3,585 infants, representing 6.3% of those who initially underwent the procedure. This is a noteworthy figure. Repeat intervention may reflect persistent symptoms, uncertainty about procedural adequacy, wound reattachment, reassessment of anatomy, or a mismatch between the original indication and the true cause of feeding difficulty. In any case, a repeat-procedure rate above 6% suggests that initial intervention does not reliably resolve concerns in a meaningful subset of infants.
Feeding-related hospital contacts were more frequent after frenotomy
Hospital contacts related to feeding difficulties or poor weight gain were more common among infants who had frenotomy than among controls. This result should not be interpreted as evidence that frenotomy worsens feeding; confounding by indication is the most likely explanation. Infants selected for frenotomy presumably had more severe or persistent feeding concerns at baseline. Nonetheless, the finding is clinically important because it challenges any assumption that frenotomy alone typically resolves the broader clinical problem. These infants remain a high-need group requiring follow-up and multidisciplinary support.
Clinical Interpretation
The study does not directly test efficacy, but it raises a central clinical question: why has frenotomy become so common in the absence of strong evidence for large, durable benefits across broad infant populations? Randomized evidence to date has generally suggested that frenotomy may improve short-term maternal nipple pain and, in some settings, breastfeeding mechanics, but effects on sustained breastfeeding success and infant growth are less certain. The evidence base is also limited by small trials, variable diagnostic criteria, heterogeneous outcome definitions, and challenges with blinding.
Therefore, the Danish findings are best understood as evidence of a rapidly expanding intervention under conditions of persisting clinical uncertainty. The large geographic differences are especially difficult to reconcile with a tightly defined, uniformly recognized disease entity. If ankyloglossia requiring frenotomy were being diagnosed and treated on highly consistent biologic grounds, one would expect much narrower variation.
For pediatricians, neonatologists, family physicians, lactation consultants, and otolaryngologists, this study supports a more deliberate approach. Assessment should move beyond the appearance of the frenulum alone and include a structured feeding evaluation, maternal symptoms, infant milk transfer, weight trajectory, and the quality of lactation support already provided. A visible frenulum is common; a clinically significant restriction causing persistent feeding dysfunction is a narrower diagnosis.
Strengths and Limitations
Strengths
The main strengths are the national scope, inclusion of all births across an 11-year period, and linkage within a universal health care system. These features minimize selection bias, permit robust incidence estimation, and enable meaningful small-area geographic comparisons. The matched-control analyses also provide useful context for selected adverse events and downstream health care use.
Limitations
Several limitations should temper interpretation. First, registry data do not capture breastfeeding technique, latch quality, maternal nipple pain, the severity of tongue restriction, or details of nonprocedural management before referral. Second, the study cannot determine which procedures were appropriate or beneficial. Third, confounding by indication is highly relevant when comparing postprocedure feeding-related contacts with controls, since infants selected for frenotomy were likely more symptomatic at baseline. Fourth, procedural coding may not capture nuances such as posterior tongue-tie classification, procedural method, or postoperative care recommendations. Finally, the findings arise from Denmark’s health system and may not generalize directly to countries with different referral structures, reimbursement policies, or newborn feeding support models.
Practice and Policy Implications
At a systems level, the findings argue for better implementation of evidence-based care pathways for infant feeding difficulty and suspected ankyloglossia. Such pathways would ideally include standardized diagnostic criteria, mandatory documentation of feeding dysfunction, early access to lactation expertise, and explicit thresholds for specialist referral and procedure. Given that most frenotomies in this study were performed in private practice, outpatient quality standards and audit mechanisms may be particularly important.
The geographic variation also suggests an opportunity for benchmarking and feedback. Municipal and regional data could be used to identify unusually high-use areas for further review. High rates do not automatically imply poor-quality care, but they warrant examination of diagnostic consistency, patient selection, and whether nonprocedural feeding support is readily available and systematically attempted.
For researchers, the next step is not another utilization study alone, but more definitive comparative effectiveness work. Trials should enroll infants with clearly defined functional impairment, use standardized diagnostic tools, measure both maternal and infant outcomes, and assess medium-term breastfeeding duration, growth, and health service use. Observational studies can also help if they include richer clinical detail than administrative registries typically allow.
Funding and Trial Registration
The abstract does not report a ClinicalTrials.gov registration number, which is expected because this was an observational registry-based cohort study rather than an interventional trial. Specific funding information is not provided in the abstract and should be confirmed from the full publication for formal citation.
Conclusion
This nationwide Danish study shows that infant frenotomy has moved from a relatively selective intervention to a common early-life procedure, with rates more than doubling over the last decade. The intervention appears generally safe in terms of severe acute complications, but it is not risk-free, repeat procedures occur in a meaningful minority, and feeding-related health care use remains elevated among infants who undergo the procedure.
The most important message is not simply that frenotomy is increasing, but that its use varies widely across geography in a way that strongly suggests clinical uncertainty and inconsistent thresholds for intervention. In a field where evidence for broad effectiveness remains limited, these data support more cautious patient selection, stronger multidisciplinary feeding assessment, and better alignment of practice with evidence. For clinicians and health systems alike, the priority should be ensuring that frenotomy is reserved for infants most likely to benefit, rather than becoming a default response to the complex and often remediable challenges of early breastfeeding.
References
1. Sonne H, Pottegård A, Hjuler T, Zachariassen G, Kildegaard H. Temporal Trends and Geographic Variation in Frenotomy Procedures Among Infants. JAMA Otolaryngology–Head & Neck Surgery. 2026;152(5):530-534. PMID: 41854600.
2. O’Shea JE, Foster JP, O’Donnell CPF, Breathnach D, Jacobs SE, Todd DA, Davis PG. Frenotomy for tongue-tie in newborn infants. Cochrane Database of Systematic Reviews. 2017;3(3):CD011065.
