The baby in the pram started

[Bassim]

Would you please correct the mistakes in my sentences?

The baby in the pram started crying loudly. The mother picked it up in her arms and rocked it gently, whispering some soothing words.

 

[Skrej]

They look okay. I might say 'its mother' instead of 'the mother', but your version is okay.

 

[Lynxear]

Your sentence is fine except I would use the infinitive "to cry" instead of the gerund form. In addition I would remove the comma.

The baby in the pram started to cry loudly. The mother picked it up in her arms and rocked it gently whispering some soothing words.

 

[Rover_KE]

I think the comma is mandatory.