Den gravide kvinde venter udenfor.

Because the noun phrase is definite.

• en gravid kvinde = a pregnant woman
• den gravide kvinde = the pregnant woman

Here den is the definite article used with a common-gender noun when an adjective comes before the noun. It is not the pronoun meaning it or that in this sentence.

In Danish, adjectives often change form depending on how they are used.

Here, gravide is the form used in a definite noun phrase:

• en gravid kvinde
• den gravide kvinde

So the -e ending appears because the phrase is definite. You also often see -e in the plural.

Compare:

• en gravid kvinde = indefinite singular
• den gravide kvinde = definite singular
• kvinden er gravid = after er, the adjective is back to gravid

Because Danish normally does not use the suffixed definite ending on the noun when there is a definite article plus an adjective before it.

So:

• kvinden = the woman
• den gravide kvinde = the pregnant woman

This is a very common Danish pattern:

• bilen = the car
• den røde bil = the red car

So once you have den/det/de + adjective, the noun usually stays in its basic form.

It is an en-word (common gender).

That is why you get:

• en kvinde
• kvinden
• den gravide kvinde

If it were an et-word, you would expect et in the indefinite and det in the definite phrase with an adjective.

Venter is the present tense of vente.

• infinitive: at vente
• present: venter
• past: ventede

Danish verbs do not change for person the way English verbs sometimes do. So you say:

• jeg venter
• du venter
• hun venter
• de venter

The verb form stays the same.

Yes, this sentence has a very straightforward main-clause order:

Den gravide kvinde + venter + udenfor

So it is basically:

subject + verb + adverb

But Danish has an important V2 rule in main clauses: the finite verb is usually in the second position. That means if you move another element to the front, the verb still stays second:

• Den gravide kvinde venter udenfor.
• Udenfor venter den gravide kvinde.

That second version is also correct.

Here udenfor is an adverb meaning outside.

It tells you where the waiting is happening:

• Hun venter udenfor.
• De står udenfor.

It is not a noun, so it does not need an article.

Here it means waits.

Even though the English sentence could sound a bit funny because pregnant and expecting are related ideas, the Danish sentence is clear:

• gravide tells you she is pregnant
• venter udenfor tells you she is waiting outside

So venter in this sentence is just the normal verb to wait. If Danish wants to express expecting a baby, it usually makes that explicit, for example venter barn.

You would say:

En gravid kvinde venter udenfor.

Notice the two changes:

• den becomes en
• gravide becomes gravid

So the definite phrase and the indefinite phrase look like this:

• en gravid kvinde
• den gravide kvinde