Unais Sheikh, a rag picker from the Rafiq Nagar slum in Govandi, woke up on Tuesday morning to discover that his son Asif, seven months old, was no longer breathing.
After battling a cold and fever for several days, he had finally died.
He weighed just six kilograms, according to community health workers from Apnalaya, a non-profit that works in the slum.
This means that he was malnourished, based on the World Health Organization standards used by the Indian government.
Asif's death comes just four days after Sahil Salman, 15 months old, who lived in the same slum, and 10 days after Khatija Afzal, two-and-a-half years old, died in similar circumstances, as recorded by Apnalaya.
Besides bad sanitation and poor access to water and health care services, which make children vulnerable to infection, the recent drop in temperatures has added to the stress on their immune systems, said doctors.
"If these children don't have sufficient clothing or shelter, the cold could make them more vulnerable to infections such as pneumonia," said Dr Girish Ambe, a health officer with the municipal corporation.
"The fact that these children are malnourished means that they need access to nutritious food more than health care, which is the job of the Integrated Child Development Services scheme," he, however, added.
The officer in charge of the Integrated Child Development Scheme in the slum, which is the premier scheme responsible for providing nutrition to children below the age of six, did not respond to calls or text message that we sent him.
"While the official cause of death is often reported as pneumonia or respiratory tract infection, malnutrition is the underlying killer," said Dr Shobha Udipi, head of the food and nutrition department at SNDT university, who conducted a study of urban malnutrition two years ago.
Built on the foothills of a dumping ground, Rafiq Nagar is a breeding ground for infection.
Because it is unrecognized and its residents face the constant threat of their homes being demolished, their huts are made with flimsy material such as tarpaulin and wooden planks, which do not shelter these children from the cold sufficiently.
At the same time, most of its residents are recognized by the civic body as rag pickers, who play an integral role in the city's waste management.