Nací en mayo.

Nací is the preterite (the simple past) of nacer.

Here it means I was born, and Spanish uses the preterite because birth is seen as a single completed event in the past.

• nacer = to be born
• nací = I was born

Spanish often expresses this idea with the verb nacer directly, not with a separate verb like to be plus a past participle.

So instead of building it like English I was born, Spanish simply says:

• nací = literally I was-born / I came into being by birth

That is the normal and natural way to say it.

Spanish often leaves out subject pronouns because the verb ending already tells you who the subject is.

In nací, the ending -í shows that it means I.

So:

• Nací en mayo. = I was born in May.
• Yo nací en mayo. = also correct, but yo adds emphasis or contrast

You would include yo only if you want to stress I, for example:

• Yo nací en mayo, pero mi hermano nació en junio.

Spanish uses en with months to mean in.

So:

• en mayo = in May
• en abril = in April
• en diciembre = in December

This is the normal preposition for months, years, and many other time expressions.

When Spanish talks about months in a basic time expression, it usually does not use an article.

So you say:

• Nací en mayo.
• Llegamos en agosto.

Not:

• en el mayo ❌

An article can appear in other contexts, but in a simple phrase meaning in May, you normally just use en + month.

In Spanish, the names of months are normally written in lowercase.

So:

• mayo
• junio
• septiembre

This is different from English, where May and June are capitalized.

The accent mark shows the correct stress: na-CÍ.

It is also part of the standard spelling of this verb form. Many first-person preterite forms of -er and -ir verbs end in -í:

• comí
• viví
• nací

Without the accent, naci would be misspelled.

In most of Spain, nací is pronounced approximately nah-THEE.

A rough guide:

• na = like nah
• cí = thee in most of Spain, because c before i is usually pronounced like the th in thin

So:

• nací ≈ nah-THEE

In parts of Spain, and in Latin America, you may hear nah-SEE instead. Both are normal in their own varieties of Spanish.

Nacer is mostly regular, but learners should be careful because some forms are less predictable.

For this sentence, nací is straightforward and follows the normal preterite pattern for an -er verb.

A few useful forms:

• nací = I was born
• naciste = you were born
• nació = he/she was born

But in the present tense, the yo form is irregular:

• nazco = I am born / I’m being born (rare in normal use, but grammatically correct)

So it is not perfectly regular in every tense.

Yes. Yo nací en mayo is grammatically correct.

The difference is mainly emphasis:

• Nací en mayo. = neutral
• Yo nací en mayo. = emphasizes I

For example, if you are contrasting yourself with someone else, yo makes sense:

• Yo nací en mayo y ella nació en julio.

Normally, no. He nacido en mayo sounds unnatural for this meaning.

For birth, Spanish usually uses the preterite:

• Nací en mayo. ✅

Birth is treated as a finished event in the past, so the preterite is the normal choice.

The infinitive is nacer, meaning to be born.

So the sentence is built from:

• nacer → nací

That is the first-person singular preterite form.

A natural way would be:

• ¿Naciste en mayo? = Were you born in May?

If you want to ask more generally, you could say:

• ¿En qué mes naciste? = What month were you born in?

So nací becomes naciste when talking to you.