A study of 264 mother-infant pairs found no association between the anatomical features of a newborn’s upper lip frenulum the small band of tissue connecting the upper lip to the gum and breastfeeding difficulties reported by mothers. The factor most closely linked to breastfeeding problems was not infant anatomy at all, but whether the mother had breastfed a previous child.
Most parents and clinicians assumed an infant’s upper lip-tie physically restricts breastfeeding and requires surgical intervention, but this paper shows lip anatomy has little to no association with feeding success compared to the mother’s prior breastfeeding experience.
The question has practical urgency. The upper lip-tie, or maxillary frenulum, is a piece of connective tissue present in all newborns, varying considerably in thickness and flexibility. In recent years, surgical procedures to cut this tissue called frenotomy have grown more common globally, on the premise that a tight or thick frenulum can restrict an infant’s lip movements and interfere with breastfeeding. The evidence base for this practice has, however, remained disputed.
Prior research on oral anatomy and breastfeeding has concentrated mainly on tongue-tie (ankyloglossia), where the tissue tethering the tongue to the floor of the mouth is unusually short or tight. A smaller number of studies looked at upper lip-tie specifically. Several suggested an association between oral ties broadly and breastfeeding difficulties, but most had not accounted for maternal factors such as previous breastfeeding experience, and few included control groups.
This study a substudy of the ongoing Lingual Frenulum in Newborn Infants (LINNE) project — was conducted at Oulu University Hospital in Finland, the main maternity hospital for a region of roughly 500,000 people. Between August 2023 and January 2024, study physicians enrolled 264 consecutive mother-infant pairs from the maternity ward. Eligible infants were full-term (37 weeks’ gestation or older) and healthy; premature infants, those with major anomalies, and non-breastfeeding mothers were excluded. Recruitment generally occurred during office hours, not on nights or weekends.
Each infant underwent a detailed clinical examination of the maxillary frenulum. Physicians assessed tissue thickness on a four-point scale (ranging from thin and membranous at under 1 millimeter to very thick with multiple tissue types at over 3 millimeters), measured the frenulum’s point of attachment on the gum, and evaluated upper lip elasticity by turning the lip upward toward the nose. They also documented whether the lip skin went pale when stretched, whether sucking pads were present, and whether mothers needed to manually reposition the infant’s upper lip during feeding. Tongue-tie examinations occurred simultaneously. Mothers completed a validated breastfeeding symptom scale at enrollment, and a follow-up questionnaire was emailed to families at six months.
The results showed no statistically significant association between any measured upper lip-tie characteristic and breastfeeding problems — not frenulum thickness, not attachment position, not lip elasticity, not lip pallor when stretched, not the presence of a sucking pad, and not whether the mother needed to correct the lip position. This held across all categories in both unadjusted comparisons and binary logistic regression.
What did differ between the groups was maternal history. Mothers who reported no breastfeeding problems had more often previously breastfed a child: 77.8% compared with 50.9% among those with problems (P = .003). In logistic regression, each additional child previously breastfed was associated with a modestly lower odds of breastfeeding problems (odds ratio, 0.80; 95% CI, 0.67–0.96; P = .02). No infant physical characteristic reached significance.
Breastfeeding problems were common across the cohort. Of the 264 mothers, 228 (86.4%) reported difficulties on the symptom scale. Tongue-tie but not upper lip-tie was associated with those difficulties: all 43 infants who required early tongue-tie treatment were in the problem group (P = .004).
Over the six-month follow-up period, only four infants (1.5%) underwent upper lip-tie surgery, all for continuing breastfeeding difficulties. Three of those four also had tongue-tie procedures performed simultaneously, making it impossible to evaluate what role, if any, the upper lip surgery played in any improvement.
The researchers concluded that, in their population of healthy, full-term infants, a harmful isolated upper lip-tie was rare, and that upper lip anatomy played a minor role in breastfeeding problems. As the paper states, “maternal breastfeeding inexperience rather than upper lip anatomy was associated with the incidence of breastfeeding problems.” The authors also noted that discussions with mothers revealed a common reason for the few frenotomies that did occur was “just in case” or performing the procedure alongside tongue-tie surgery indications they described as lacking controlled evidence.
The study has several limitations the authors explicitly acknowledge. It was conducted at a single hospital, which may affect how broadly the findings apply, though the authors note that the hospital serves more than 90% of local deliveries and that selection criteria were not used to filter participants. The researchers developed their own clinical assessment scale rather than using a pre-existing standardized classification, which complicates direct comparisons with prior studies. Only one physician evaluation per infant was performed, creating the possibility of observer bias. Follow-up responses were received from 57.6% of families, meaning some surgeries performed in private clinics may not have been captured. And because the four infants who did undergo lip-tie surgery also had concurrent tongue-tie procedures (with one exception), the independent effect of the lip-tie release on breastfeeding outcomes could not be assessed.
Reference:
Niemelä L, Lohi V, Aitamurto S, Lehtinen A, Aikio O. Upper Lip Frenulum Findings and Breastfeeding Problems in Healthy Newborns. JAMA Network Open. 2026;9(5):e2613308. doi:10.1001/jamanetworkopen.2026.13308
