Five more babies died at West Bengal government-run Malda Sadar Hospital, taking the toll to 40 in the last 10 days, officials said.
Hospital authorities said four of the infants, which died since last night, were less than 15 days old.
Almost all the babies were born underweight and suffered from broncho pneumonia and were brought from interior areas of Malda district, the officials said.
The hospital authorities said an average 60 sick babies were admitted daily and their total number exceeded the capacity by three times.
They said to cope with the situation, the number of beds, doctors and nurses were being increased in the hospital.