English to Italian Medical Medical (general) anatomia

Per descrivere le proporzioni corporee nelle varie fasi di sviluppo trovo:

In pediatrics, the postnatal period is divided into stages of development.
In the different stages of development the body changes length continuously.
(1) neonatal period (the first two weeks of life), (2) infancy (up to the end of the first year of life), (3) early childhood (up to the end of the fifth year of life), (4) school age (up to the onset of puberty), (5) puberty (maturation into adult, length varies), (6) adolescence (completion of the development and growth in length of the skeletal system up to (7) adults.

prima infanzia (...), seconda infanzia? Vedo che non c'è molta corrispondenza di concetto fra inglese e italiano...
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