A new study published in the Oxford University Press journal Human Reproduction finds that depressed pregnant women have twice the risk of preterm delivery than pregnant women with no symptoms of depression. The study was conducted by the Kaiser Permanente Division of Research.
The study found that pregnant women with symptoms of depression have an increased risk of preterm delivery, and that the risk grows with the severity of the depressive symptoms. These findings also provide preliminary evidence that social and reproductive risk factors, obesity, and stressful events may exacerbate the depression-preterm delivery link, according to the researchers.
Because the majority of the women in the study did not use anti-depressants, the research provides a clear look at the link between depression and preterm delivery.
The study — which is among the first to examine depression and pre-term delivery in a representative and diverse population in the United States — looked at 791 pregnant Kaiser Permanente members in San Francisco city and county from October 1996 through October 1998.
"Preterm delivery is the leading cause of infant mortality, and yet we don’t know what causes it. What we do know is that a healthy pregnancy requires a healthy placenta, and that placental function is influenced by hormones, which are in turn influenced by the brain," said lead author Dr. De-Kun Li, a reproductive and perinatal epidemiologist at Kaiser Permanente’s Division of Research in Oakland.
"This study adds to emerging evidence that depression during 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 labor," Li explained.
In addition to being the leading cause of infant mortality and morbidity, preterm delivery is also the leading medical expenditure for infants, with estimated annual cost of about $26 billion in the United States alone. Presently, other than a prior history of preterm delivery and some pregnancy complications, very little is known for its risk factors and origins.