Is it normal for babies to bite things?

Dear Dr. Donya,

Thank you very much for your reply to my earlier question about my daughter. I have one more question: is it normal for my baby (she is now more than three months old) to bite things? She really likes chewing my finger, as if her gum was itchy.

-- Yulie

Dear Yulie,

Yes, it is normal for a three-month-old child to chew on things because this age is called the "oral stage" and she wants to explore by tasting everything and because her teeth may be newly arriving. You should look for toys to give her that are not dangerous or toxic if placed in the mouth.

-- Dr. Donya

Dear Dr. Donya,

A couple I know have a baby girl with autism. I know what it is, but I still don't know how it happens. Does it occur because the mother was unhealthy during pregnancy, there was a virus in the womb or what?

-- Rina

Dear Rina,

Thirty years ago, "refrigerator mothers" -- mothers who were considered distant and cold and who showed little affection -- were thought to be the cause of autism. But autism has no single cause. Researchers believe that several genes and environmental factors such as viruses and chemicals may contribute to the development of the disorder.

-- Dr. Donya