Clipping of the tongue-tie is a common procedure that neonatologists perform in our neonatal unit to help establish breastfeeding. It is a painful technique where the measures healthcare providers usually perform to control pain (such as sucking) cannot be done at the time of the clipping because the technique is performed on the tongue. The aim of this study was to prove that inhaled lavender essential oil during the clipping of the tongue-tie can help control pain. Participants were newborns born at our hospital during the study period. They were offered to participate and enrolled in the study if their parents agreed to and signed an informed consent. The use of inhaled lavender essential oil is safe. No side effects have been found with its use. The procedure of the frenotomy did not change for patients who were enrolled in the study. By demonstrating that inhaled lavender essential oil helps reduce pain, its use was included as part of the regular measures to control pain during frenotomies at our neonatal unit (Hospital del Mar, Barcelona, Spain). The study started in August 2020 and ended in April 2021.

This randomized clinical trial was conducted with the neonates born at our hospital or less than 15 days old who underwent a frenotomy for type 3 tongue-ties according to Coryllos classification and the Hazelbaker tool during the study period (August 2020 to April 2021). Healthcare providers assessed pain by means of crying time and the highest Neonatal Infant Pain Scale (NIPS) score in the five minutes post procedure, and whether there was an increase in heart rate (HR) and decrease in oxygen saturation (satO2). NIPS evaluates facial expression, crying, breathing pattern, arm and leg position, and state of arousal on a scale from 0 to 7, where 0-2 means no pain to mild pain, 3-4 mild to moderate pain, and >4 severe pain. In an exploratory preliminary study prior to the intervention, a mean (SD) crying time of 19.80 (21.14) seconds was observed. In order to detect a difference of 10 seconds in crying time, a sample size of 71 patients per group was required in order to draw conclusions with a CI 95% and a power of 80%. Patients were enrolled if their parents agreed to and signed a written informed consent.

Data were recorded on demographic (gender, gestational age, birth weight, age in hours at the time of frenotomy) and clinical variables (HR and satO2 before, during, and after the procedure, whether there was crying or not during the procedure, length of crying time in seconds, presence of side effects during the procedure (apnea, desaturation, others) and highest NIPS score within the first 5 minutes after the procedure). The independent variable was the use or not of aromatherapy during frenotomy. The dependent variables were: HR and satO2 pre and post procedure, presence of crying and duration, hours of life at the time of the frenotomy, and the NIPS score. The controlled variables were gestational age, sex, and birth weight.

All the newborns are assessed for the presence of ankyloglossia as part of the routine neonatal evaluation and a frenotomy is offered to all tongue-tied patients. The examiner grades the ankyloglossia based on Coryllos's criteria and the Hazelbaker tool to assess its impact on tongue movement and on breastfeeding. A lingual frenulum is symptomatic if it scores 8 points or less in appearance and/or 11 points or less in function according to Hazelbaker. Advice and help with positioning and attachment for breastfeeding is provided to all the mothers by IBCLC (International Board Certified Lactation Consultant) nurses. During the study period, if a patient with a type 3 tongue-tie was identified, the patient's parents were offered to participate in this study. Accepted patients were allocated into case or control group by simple random sampling using the program OxMAR (Online Minimization and Randomization for Clinical Trials). During the frenotomy the neonate was taken to the neonatal unit and monitored with a pulse-oximeter (COVIDIEN Nellcor Portable SpO2 Patient Monitoring System PM10N, Covidien Ireland Limited, IDA Business & Technology Park, Tullamore, Ireland) before, during and after the procedure. For both groups, neonates were swaddled, administered 1 mL of oral sucrose, and allowed to suck for 2 minutes prior to the procedure. The experimental group also had a 7 x 7 cm gauze pad with 1 drop (43.75 mg) of 100% pure LEO (Pranarôm España S.L.) placed 2 cm under their nose for 2 minutes prior to starting the frenotomy and for the duration of the procedure. The bottle of LEO has a dropper that always dispenses the same amount of oil per drop. The procedure did not start the procedure until the patients were calm and had a NIPS score of 0. Frenotomy was performed by one of the three staff neonatologists using Coryllos' technique: placing a sterile groove director under the tongue straddling the frenulum, holding the frenulum in place with visualization of tongue base and frenulum, and snipping the frenulum with a scissor along the underside of the tongue to its base just proximal to the genioglossus muscle, until a full release is achieved. Once the procedure was completed, the gauze pad was removed and vital signs, whether the baby cried or not, the seconds crying lasted, and the post procedure NIPS score were registered on a data collection sheet. If a neonate cried, calming techniques such as holding, swaddling, and sucking were employed. Following the frenotomy, the neonate was returned to the mother for breastfeeding.

Statistical analysis: Quantitative variables (gestational age, birth weight, age at frenotomy, heart rate pre and post-procedure, increase in heart rate post-procedure, oxygen saturation pre and post-procedure, decrease in oxygen saturation post-procedure, and duration of crying) are described using the mean, standard deviation, and 95% confidence interval (CI); case vs control groups were compared with a Student's t test. Gender, the presence of crying, and adverse effects between the two groups are presented in percentages and compared using Fisher's exact test. NIPS scores between cases and controls were compared with the Wilcoxon rank-sum (Mann-Whitney) test. Statistical significance was set for a p <0.05. Statistical analyses were performed using STATA version 15.1 (StataCorp, College Station, TX, USA).

Our hospital Ethics Committee (CEIm-PSMAR) approved this study (reference code: 2020/9373/I). Prior to patient enrollment, a signed informed consent was obtained from the neonate's parents. This study was conducted according to the ethics code of the Barcelona Medical Association and the principles of the Helsinki-Fortaleza Declaration 2013.

Inclusion Criteria:

• Healthy full-term neonates born at Hospital del Mar (Barcelona, Spain), or less than 15 days old who had been discharged and returned for the frenotomy, who underwent a frenotomy for type 3 tongue-ties according to Coryllos classification and the Hazelbaker tool during the study period (August 2020 to April 2021)

Exclusion Criteria:

• Refusal of the patient's parents to participate