Nail Cutter and a Mother

We were in the postoperative ward seeing operated patients. There was a patient who had undergone a cesarean section two days ago. She was standing next to her bed. She was OK. The baby was wrapped up in a blanket. It also looked OK. Something caught my attention. It was a nail cutter.
“What is that for?” I asked.
She smiled and said something I could not hear.
“It is for warding off evil” my Registrar told me.
“Huh?” I said and looked at the patient questioningly.
“A metal object kept in the bed wards off evil, she believes” my Registrar said.
“Is that so?” I asked the patient. I thought I had seen all sorts of customs and beliefs of mothers and their relatives. This was a new one.
“Yes” the woman admitted.
“But the cot is made of metal” I said. “Is that not enough?”
“It has to be on the mattress, where the baby is kept.”
“Uh…” I said.
“She had fever two days ago” my Registrar continued. “Now she is afebrile.”
“After she put that nail cutter there?” I asked. I got a smile for an answer.
“Be careful. Do not cut the baby’s nails with it” I told the woman. She shook her head. “Some relative may come to see you, find that your baby’s nails are long, and may cut them with this while you are not looking” I warned.
“I will take it away and put a spoon in its place” she promised.