Learn Spanish (Spain): El parto duró doce horas. - The labor lasted twelve hours.

In English, 'labor' refers to both work and childbirth. In Spanish, el parto specifically means 'childbirth' or 'delivery'. Watch out because it is a false friend: it looks like the English word 'part', but the Spanish word for 'part' is la parte.

Why is the preterite tense duró used here instead of the imperfect duraba?

The preterite duró is required because the sentence gives a specific, completed duration (doce horas). You would only use the imperfect duraba if you were describing an ongoing situation in the past without a defined end, such as setting the background scene in a story.

Can I add por or durante before doce horas?

You could add durante, making it duró durante doce horas, but Spanish speakers usually omit the preposition after the verb durar since the verb itself already implies a span of time. You should avoid using por to express duration here, as it sounds unnatural in Spain.