neonatal
Concise Oxford English Dictionary © 2008 Oxford University Press:
neonatal /ˌniːə(ʊ)ˈneɪt(ə)l/
▶adjective relating to newborn children (or mammals).
– derivatives
neonatally adverb,
neonatologist noun,
neonatology noun.
neonatally adverb,
neonatologist noun,
neonatology noun.
'neonatal' also found in these Oxford entries:

