Medically speaking, intersex is defined as "congenital anomaly of the reproductive and sexual system." There is no standard "intersex body" because being born with ambiguous sex can present itself in many different ways.
Including, but not limited to external genitalia, internal reproductive organs, or an endocrine system that is different from most other people of that sex. Due to the vague defining boundaries of intersex, it's difficult to determine specific statistics on this population.
However, it is estimated that about one in 2,000 children (5 children per day) are born visibly intersex in the United States. [Cit.]