Утром няня отвезла малыша к педиатру, потому что ночью у него был кашель.

In Russian, some time expressions use the instrumental case to mean in the morning / in the evening / at night.

So:

• утро = morning
• утром = in the morning

This is a very common fixed pattern:

• утром = in the morning
• днём = in the daytime / during the day
• вечером = in the evening
• ночью = at night

So Утром няня отвезла малыша... means In the morning, the nanny took the child...

Няня usually means nanny, babysitter, or sometimes childminder, depending on context.

It refers to a person who takes care of a child. In many contexts it suggests a woman, though the word is mainly understood by role rather than as a strongly grammatical gender issue for the learner here.

In this sentence, няня is the subject:

• няня отвезла = the nanny took / drove

The verb отвезла comes from отвезти, which means to take someone somewhere by transport and usually implies taking them away to a destination.

Here is the basic contrast:

• везти / везла = to be transporting / carrying by vehicle, focusing on the process
• отвезти / отвезла = to take someone somewhere by vehicle and complete the trip
• привезти / привезла = to bring someone/something to a place

In this sentence, the nanny took the child to the pediatrician, so отвезла fits well because it is:

• perfective
• focused on a completed action
• specifically about transporting someone to a destination

The feminine past ending -ла agrees with няня.

Малыша is the accusative singular form of малыш.

Because малыш refers to an animate masculine noun, its accusative singular looks like the genitive singular:

• nominative: малыш
• accusative: малыша

Since the child is the direct object of отвезла, Russian uses the accusative:

• няня отвезла малыша = the nanny took the little child / baby

This is a very important pattern in Russian: for animate masculine nouns, the accusative often matches the genitive.

Малыш literally means something like little child, little one, toddler, or sometimes baby, depending on context.

It is a warm, everyday word, not a medical or formal one. In this sentence, it suggests a young child, which fits naturally with педиатр.

So малыша here is best understood as the child or the little one.

The preposition к takes the dative case and usually means to, toward, or to the place/person for a visit.

So:

• педиатр = pediatrician
• к педиатру = to the pediatrician

This construction is very common when going to a person, especially professionals:

• к врачу = to the doctor
• к учителю = to the teacher
• к другу = to a friend
• к педиатру = to the pediatrician

So отвезла малыша к педиатру means took the child to the pediatrician.

Потому что means because.

It introduces a clause giving the reason for something:

• няня отвезла малыша к педиатру, потому что ночью у него был кашель
• the nanny took the child to the pediatrician because he had a cough at night

This is one of the most common ways to say because in Russian.

You may also see:

• так как = since / because
• из-за того что = because of the fact that

But потому что is the most basic and common choice in everyday speech.

Ночью is another standard time expression in the instrumental case, meaning at night or during the night.

Compare:

• утром = in the morning
• ночью = at night

So потому что ночью у него был кашель means because he had a cough during the night.

This is just the normal idiomatic way to say it in Russian.

Both are possible in Russian, but they mean slightly different things.

• у него был кашель = he had a cough
• он кашлял = he was coughing / he coughed

The sentence uses у него был кашель because Russian often expresses symptoms as something a person has using the pattern:

• у + genitive + был/была/было

Examples:

• у него была температура = he had a fever
• у неё была головная боль = she had a headache
• у ребёнка был насморк = the child had a runny nose

So у него был кашель sounds very natural when talking about a medical symptom.

У него literally means by him, but in this kind of sentence it means he has / he had.

Here it refers to малыша. So:

• у него был кашель = the child had a cough

Russian often uses this possession/condition structure instead of a verb like to have.

Grammatically:

• он = he
• него = genitive form used after у

So:

• у него = he has / with him there is

In context, it clearly refers to the child, not the nanny.

Because кашель is a masculine noun.

So in the past tense, быть agrees with it:

• был for masculine
• была for feminine
• было for neuter
• были for plural

Examples:

• был кашель = there was a cough
• была температура = there was a fever
• было воспаление = there was an inflammation

So у него был кашель is correct because кашель is masculine.

The word order here is natural, but Russian allows some flexibility.

Current order:

• Утром няня отвезла малыша к педиатру, потому что ночью у него был кашель.

This sounds neutral and clear:

• first the time
• then the subject and action
• then the destination
• then the reason

You could rearrange parts for emphasis, for example:

• Няня утром отвезла малыша к педиатру...
• Потому что ночью у него был кашель, утром няня отвезла малыша к педиатру.

These are also grammatical, but the original version is probably the most straightforward and natural for ordinary narration.

Both are possible, but they are not identical.

• врач = doctor
• педиатр = pediatrician

Педиатр is more specific, so it makes sense here because the patient is a child. In everyday conversation, people might still say к врачу if the exact specialty is not important.

So:

• к врачу = to the doctor
• к педиатру = to the pediatrician

The sentence chooses the more precise word.