WASHINGTON — For decades, health experts have tried to determine why African-American babies are twice as likely to die as white infants. A new series of studies from the Joint Center for Political and Economic Studies' Health Policy Institute, along with a small but growing number of neonatalogists nationwide, suggests that the stressful effects of racism play a role. "That's the elephant in the room," said Michael Lu, an obstetrician-gynecologist and professor at the University of California at Los Angeles who studies disparities in infant health. "When we're studying racial disparities, for decades people have looked at stress and infant...