Nail features in healthy term newborns: a single-centre observational study of 52 cases

Introduction The anatomy and embryology of the nail are well known, and nail abnormalities are a feature of many genodermatoses. However, the physiological aspect is not well described. We aimed to analyse the physiological features of nails in healthy newborns. Methods We performed an observational, prospective study at University Hospital Center of Tours between July and October 2015. Newborns were included by a dermatologist assistant during the systematic examination on release of the mother from the hospital. The medical history of the mother and infant were recorded by using a standardized questionnaire. Finger-and toenails were systematically photographed for a second interpretation by a dermatologist with blinding to the first photograph. Results Fifty-eight patients were eligible, and 52 were included. Half of the newborns were males, and the mean age at inclusion was 3.6 +/- 1.2 days. Fingernails had an oval shape (71.1%) or a flat curvature (63.5%), and half had a lunula. Toenails showed an apparent hypertrophy of the proximal nail fold (38.4%) and lateral nail fold (73.1%). The shape of the nails was triangular (50.0%) or round (21.1%). We noted koilonychia in 32.7% of infants and lunula in 7.7%. Distal parts showed onychoschizia (28.8%) and onycholysis (26.9%). Conclusion Koilonychia, onychoschizia of toenails or absence of lunula are physiological features of nails in newborns.