Loss

A feeling of emotional deprivation that is experienced at some point in time. For a birth parent the initial loss will usually be felt at or subsequent to the placement of the child. Adoptive parents who are infertile feel a loss in their inability to bear a child. An adopted child may feel a sense of loss at various points in time; the first time the child realizes he is adopted may invoke a strong sense of loss for his birth family.

Source: Children Welfare Information Gateway