Why doctors recommend breast feeding during initial period of infant growth?

Menstrual cycle temporarily ceases till parturition and thereafter for the period of breast feeding.

A body starting with an initial velocity of 5 m//s , moves with a uniform acceleration of 2 m//s^(2) . After some time it attains a velocity of 13 m//s . Find the distance covered by the body during this period.

During a medical investigation an infant was found to possess an extra chromosome 21 . Describe the symptoms the child is likely to develop later in life. Why in females exceeding 40-45 years of age are children with Down's syndrome more likely to be born.