The condition of Aradhana has worsened, while her sister Stuti is doing well, Dr Rajiv Choudhary, director of Missionary Hospital at Padhar, told reporters.
This comes just two days after the sisters celebrated their first birthday.
Aradhana was kept on ventilator for over a week but since yesterday she was suffering from high fever and also developed infection in the blood, he said.
Her status was a matter of concern, he said, adding that strong antibiotics were being administrated to stop the infection from spreading.
A team of doctors, including Dr A Jacob from Christian Medical College (CMC), Vellore, is keeping a close watch on her, Choudhary said.
Aradhana and Stuti, who were joined at the heart and liver, were successfully separated after a day-long complex surgery conducted by a team of 34 medical experts, including 23 doctors from India and abroad, on June 20 at the Missionary Hospital in Padhar.
According to Choudhary, Aradhana's sister Stuti is keeping fine.