Findings in the American Journal of Obstetrics and Gynecology don't prove depression directly leads to preterm birth.
Fourteen-thousand women were screened for prenatal depression, and of those who screened positive, 14 percent delivered before the 37th week of pregnancy, compared to 10 percent of other women.
Researchers were able to account for other factors, such as race and age, and depression was still linked to pre-term birth risk.
