Pregnant women who are depressed are twice as likely to suffer a preterm delivery, US research suggests. For this latest study, the researchers interviewed 791 pregnant women around the tenth week of their pregnancy.
Just under half of the women, 41 per cent, reported significant or severe depressive symptoms.
Only 1.5 per cent of the women were taking antidepressants during the study, so it provides a clear look at the link between depression and preterm delivery without being influenced by drug use.
Overall, 6 per cent of the women had a preterm birth.
After adjusting for other risk factors such as smoking status, they found that women who were severely depressed were 2.2 times more likely to suffer a preterm delivery, defined as a delivery before 37 weeks, than women who were not depressed.
Lead researcher Dr De-Kun Li, from the Kaiser Permanente Division of Research in Oakland, California, said: 'This study adds to emerging evidence that depression in early pregnancy may interfere with the neuroendocrine pathways and subsequently placental function.
'The placenta and neuroendocrine functions play an important role in maintaining the health of a pregnancy and determining the onset of labour.'
Depression during pregnancy is under-recognised and under-diagnosed, warned Dr Li.
'If prenatal depression is indeed as prevalent as reported in this and other studies and doubles the risk of preterm delivery, then bringing depression to the forefront of prenatal care could lead to a significant reduction of preterm deliveries.'
Human Reproduction Online 2008.