Thyroid function is known to be affected during pregnancy. Risk of depression is particularly high for women during the prenatal period.

Various investigators have attempted to establish a link between thyroid function and post partum depression. While the pathogenesis of postpartum mood disturbances remains unclear.

This study aimed to investigate whether thyroid function differs in women with postpartum depression compared to a control group.

In this case-control study, Forty eight patients suffering from postpartum depression according to Diagnostic and Statistical Manual of Mental Disorders, fourth edition totally revised (DSM-IV-TR), and 65 normal controls underwent diagnostic evaluation using Structured Clinical Interview for DSM-IV-TR. Then the Persian version of Edinburgh Postnatal Depression Scale (EPDS) was completed by the participants. Finally, their thyroid functions were assessed. Data analyses were done using the SPSS program 13.

No statistically significant differences were observed between thyroid function tests and postpartum depression. According to multiple regression analysis with stepwise method, subjects with lower serum TSH, T3RU and T3 levels tended to have higher EPDS scores (P-value=0.008).

The present study reports that those women with postpartum depression had a no greater prevalence of thyroid dysfunction than the control subjects. It seems that thyroid dysfunction should be considered in women with postpartum depression individually, but the role of thyroid as an important cause of this condition is not yet established. This suggests that future studies should concentrate on this concept in postpartum depression.