Is the Neonatal Tongue Screening Test a valid and reliable tool for detecting ankyloglossia in newborns?

BACKGROUND: Although there is a lack of strong evidence for the association between ankyloglossia in newborns and impaired breastfeeding, screening for ankyloglossia using the Neonatal Tongue Screening Test (NTST) is mandated by law in Brazilian maternities. AIM: To assess the reliability and validity of the NTST. DESIGN: cohort study; baseline sample comprised 268 mother-newborn dyads. At follow-up, 169 mothers were contacted by telephone. Interviews with the mothers for data collection were performed up to 48 h and at 1-3 months after childbirth. Trained and calibrated personnel performed the oral examinations of the newborns. Thirty newborns were examined for inter-reproducibility assessment. RESULTS: Of the 268 newborns included, 212 had a lingual frenulum that could be visually inspected and their NTST scores ranged from zero to nine (mean = 2.0, +/-2.0). Interexaminer reproducibility was acceptable (Intraclass correlation coefficient = 0.77). Internal consistency of the NTST was poor (Cronbach's alpha = 0.28). Construct validity was investigated through the association between NTST scores and difficulties in breastfeeding at baseline and follow-up, and infants' weight gain at follow-up (mean age 32 +/- 6.7 days). No statistically significant associations were found. CONCLUSION: NTST is neither reliable nor valid for detecting ankyloglossia that may interfere with breastfeeding in newborns.