Learn Italian: Da neonato, non avevo ancora i denti. - As a newborn, I did not have teeth yet.

The preposition da followed directly by a noun is a very common way to express a life stage or role in Italian. It translates perfectly to "as a..." or "when I was a...". Notice that you don't need an article here—it's simply da neonato, not dal neonato or da un neonato.

Why is the verb avevo in the imperfect tense rather than the passato prossimo?

The imperfect tense (avevo) is used to describe ongoing states, habits, or physical conditions in the past. Since not having teeth was a continuous physical state during your time as a newborn rather than a one-time completed action, the imperfect is the correct choice here.

Doesn't ancora usually mean "still"? Why does it translate to "yet" here?

Ancora can mean both "still" and "yet". In affirmative sentences, it usually means "still". But when it is paired with a negative word like non—as in non avevo ancora—the combination translates to "not yet".

Why is the definite article i used before denti when we don't say "the teeth" in English?