A forza di cullare il neonato, riesco a farlo dormire.

A forza di is an idiomatic expression meaning by doing something repeatedly, through persistence, or by dint of.

So in this sentence, it suggests that the result happens because of repeated rocking. It is not just while rocking; it has the nuance of after enough rocking / by keeping at it.

A similar English idea would be:

• By rocking the baby long enough...
• By dint of rocking the baby...
• After a lot of rocking...

Because the pattern is:

a forza di + infinitive

So after di, you use the infinitive form of the verb:

• a forza di aspettare
• a forza di studiare
• a forza di cullare

This is a fixed structure. English learners often expect something like a gerund, but in Italian this expression normally takes the infinitive.

Cullare means to rock, especially a baby, usually in your arms or in a cradle, in order to calm them or help them sleep.

It is more specific than a general verb like muovere. It strongly suggests the kind of gentle rocking associated with babies.

Related words:

• culla = cradle
• cullare = to rock/cradle

It can also be used figuratively in other contexts, but here it is literal.

Neonato means newborn baby or newborn.

Using il means we are talking about a specific newborn already known from the context:

• il neonato = the newborn baby

If you said un neonato, it would mean a newborn baby in a more general or newly introduced sense.

Also, neonato is a bit more specific and slightly more formal/clinical than bambino. It focuses on the fact that the child is very young, newly born.

Riesco a comes from the verb riuscire.

Pattern:

• riuscire a + infinitive

It means:

• to manage to
• to succeed in
• to be able to in the sense of actually achieving the result

So riesco a farlo dormire means not just that I have the ability in theory, but that I manage to get the baby to sleep.

This is different from posso, which usually means I can / I am allowed to / it is possible for me to.

Compare:

• Posso farlo dormire = I can get him to sleep / I’m able to in principle
• Riesco a farlo dormire = I manage to get him to sleep / I succeed in doing it

This is the causative construction:

fare + infinitive

It means to make someone do something or to get someone to do something.

So:

• fare dormire = to make someone sleep / to get someone to sleep

Then lo refers to the newborn baby:

• farlo dormire = to make him sleep / to get him to sleep

So the structure is:

• far(e) + lo + dormire

When the pronoun is attached to the infinitive fare, the final -e drops:

• fare + lo → farlo

This is very common in Italian:

• farlo
• dirlo
• vederlo

Because here the baby is treated as the direct object of fare.

With causative fare + infinitive, the person being made to do something can be either direct or indirect depending on the structure.

In this sentence:

• dormire does not take a direct object
• so the person who sleeps, il neonato, becomes the direct object of fare
• therefore the pronoun is lo

So:

• faccio dormire il neonato
• lo faccio dormire
• riesco a farlo dormire

You are more likely to see gli when the infinitive already has its own direct object, for example:

• Gli faccio mangiare la minestra = I make him eat the soup

There, la minestra is the direct object of mangiare, so him becomes indirect.

Yes, absolutely.

Both are correct:

• riesco a far dormire il neonato
• riesco a farlo dormire

The difference is just that in the second version, il neonato has been replaced by the pronoun lo.

So:

• far dormire il neonato = to get the newborn to sleep
• farlo dormire = to get him to sleep

Both are natural.

The comma separates the introductory phrase A forza di cullare il neonato from the main clause riesco a farlo dormire.

This is very natural in Italian because the first part is a kind of preliminary circumstance or means:

• By rocking the baby over and over, ...
• I manage to get him to sleep.

The comma helps readability and reflects a pause. In some short sentences punctuation can vary, but here the comma is perfectly normal and stylistically clear.

Yes, but it would not mean exactly the same thing.

Compare:

• A forza di cullare il neonato, riesco a farlo dormire.
• Cullando il neonato, riesco a farlo dormire.

The version with a forza di emphasizes persistence and repetition. It suggests that the result comes after enough rocking.

The gerund version cullando is more neutral and simply means by rocking / while rocking. It does not automatically give the idea of repeated effort as strongly as a forza di does.

Yes, it is natural and idiomatic.

It sounds like something a native speaker could say, especially if they want to stress that getting the baby to sleep takes some persistent rocking.

A few nearby alternatives are also possible, with slightly different nuances:

• Cullando il neonato, riesco a farlo dormire.
  More neutral.
• A furia di cullarlo, riesco a farlo dormire.
  Similar idea, often a bit more colloquial and emphatic.
• Se lo cullo a lungo, riesco a farlo dormire.
  More explicit about duration.

So the original sentence is both grammatical and idiomatic.