Changes in tryptophan metabolism during pregnancy and postpartum periods may be useful predictive and diagnostic markers of postpartum depressive symptoms, according to a study published in the Journal of Affective Disorders.

The study included 132 women (20 years and older) who participated in a prenatal program at the Nagoya University Hospital in Japan between October 2012 and January 2017. Investigators divided participants into 4 groups: nondepressive (n=62), postpartum depressive (n=15), temporary gestational depressive (n=22), and continuous depressive (n=33). Before delivery and 1 month after delivery, investigators collected blood samples to test whether there was an association between plasma levels of tryptophan and its metabolites and depressive symptoms during pregnancy and postpartum periods. Participants then completed the Japanese version of the Edinburgh Postnatal Depression Scale.

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In the nondepressive and postpartum depressive groups, high-performance liquid chromatography showed differences in plasma levels of tryptophan metabolites during pregnancy and postpartum periods. However, in the temporary gestational depressive and continuous depressive groups, there was no significant difference in plasma level of tryptophan or its metabolites. Compared with the nondepressive group, the postpartum depressive group had higher plasma levels of kynurenine and kynurenic acid and kynurenine/tryptophan and kynurenic/kynurenine ratios during pregnancy and lower levels of 3-hydroxyanthranilic acid during the postpartum period.

One limitation of the study was the small sample size, especially of the postpartum depressive group.

Future research could include larger numbers of participants and additional diagnostic tools to assess participants’ history of mood disorders and depression.

Reference

Teshigawara T, Mouri A, Kubo H, et al. Changes in tryptophan metabolism during pregnancy and postpartum periods: potential involvement in postpartum depressive symptoms. J Affect Disord. 2019;255:168-176.