According to the Washington Post:

The ugly wave of anti-Arab feelings immediately after Sept. 11, 2001, may have been responsible for a sharp increase in the incidence of premature and low-birth-weight babies born to women of Arab descent in the United States in the months that followed the terrorist attacks.

The evidence is circumstantial but compelling, epidemiologist Diane S. Lauderdale of the University of Chicago says in the latest issue of Demography.