Co-occurrence of congenital central hypoventilation syndrome and Hirschsprung disease is known as Haddad syndrome. Affected patients develop with variable expressivity a dysfunction of the autonomic nervous system. We report the natural history of a full-term newborn infant presenting multiple features of autonomic system dysfunction that were already noted antenatally. The presence of a nonpolyalanine repeat expansion mutation in the PHOX2B gene confirmed postnatally the diagnosis of Haddad syndrome. This case suggests that patients presenting with autonomic system dysfunction may already present signs of the disease during the fetal period. Furthermore, antenatal presentations may correlate with a more severe presentation of the disease. In conclusion, antenatal signs of dysautonomy should stimulate multidisciplinary prenatal approach to orientate proper postnatal intervention and facilitate treatment strategies.