Praise be to Allah.
If the child understands what the ‘awrah (private parts which need to be covered in public) is, then it is not permissible for a woman to uncover her ‘awrah in front of him. But if he does not understand because he is little, then it is permissible. It seems to me that at the age of 11 months he will not understand, but if a child is four or five years old, he may understand this matter. The point is that if he understands and such actions will stick in his mind, then it is not permissible for a woman to uncover the most private ‘awrah in front of him.