IgM is for immediate response to intro of antigens th eonly antibody that the new born have is IgG which comes from the mother. thats the reason why new borns are more susceptible to infections and they get pneumonia and all that easily. but antibodies later are delivered from the colostrum(1st milk from mother) and child starts forming antibodies something near 4 or 5 months i suppose. not sure as to when they start producing
and thanks for the wishes