Washington (SmartAboutHealth) - A new study published in the journal Human Reproduction has found that pregnant women who suffer from depression are twice as likely to have a premature birth.

Researchers have found a direct link between depression and the risk of premature birth. The more serious the depression, the higher the risk.

The study was led by De-Kun Li at Kaiser Permanente’s Division of Research in Oakland, California and interviewed 791 women between 6 weeks and 18 weeks of pregnancy.

A premature birth occurs when a woman gives birth within the first 37 weeks of pregnancy.

This is tied to developmental problems and other issues for the kids.

Researchers have been unable to explain why the link is there though.

Out of the 791 women who were interviewed, 41.2% were “significantly” depression, while 21.7% were in “severe” depression.

Those “significantly” depressed were 1.6 times more likely to have a preterm birth.

Women suffering from severe depression were 2.2 times more likely..

The study has been published in the journal Human Reproduction.