Biomarkers (or biological markers) are used in many fields of medicine to provide objective information on normal or pathological biological processes and to predict response to therapeutic interventions.  Researchers have long searched for biomarkers which could be used to identify women with postpartum depression (PPD) or, even better, to predict which women are at highest risk for postpartum depressive illness.  

While postpartum depression is typically thought to be triggered by hormonal shifts which occur after childbirth, levels of estrogen, progesterone, prolactin and other hormones do not appear to correlate with depressive symptoms and have not been useful for predicting which women are most vulnerable to depression in this setting.

A recent study from Chinese researchers has looked at levels of leptin in postpartum women, and this study suggests that leptin levels may have predictive value in this setting.  Leptin is a fat-derived hormone that signals satiety; typically low leptin levels are observed in women with low body mass index whereas women with obesity have higher levels of leptin.  In an earlier study, researchers observed that leptin levels inversely correlated with depressive and anxiety symptoms, and that this relationship between leptin levels and severity of symptoms remained significant after controlling for body fat or weight.

In the present study serum leptin levels were collected 24–48 after delivery in women who delivered a full-term, singleton,  live-born infant. at 3 months after delivery. The Edinburgh Postnatal Depression Scale (EPDS) was completed at 3 months postpartum,

407 women completed the study.  Based on EPDS scores, 53 women (13.0 %) had postpartum depressive symptoms at three months postpartum. Serum leptin levels in women with PPD were significantly higher than those in women without depressive symptoms (36.5 [IQR, 25.5–50.4] vs. 14.5 [IQR, 9.4–22.4]?ng/ml, P?<?0.0001).

While these findings need to be replicated in other populations, this is an interesting study.  Could we possibly use leptin levels immediately after delivery to predict risk for postpartum depression? In this study, the researchers calculated an optimal cutoff cutoff value for leptin levels which could be used to predict postpartum depressive symptoms. Using a cutoff of 24.3 ng/mL for leptin levels, the sensitivity of the test was 88.7 % and the specificity was 73.4%.  This means that leptin levels above 24.3 ng/mL would identify 88.7% of the women who would be depressed at 3 months postpartum, although 27.6% of the women identified in this manner would not go on to develop PPD.  After adjusting for potential confounders, they calculated that women with leptin levels greater than 24.3 ng/ml are about 8 times as likely to develop PPD than women with lower leptin levels (OR 8.234; 95 % CI, 3.572–15.876; P?<?0.0001). Not too bad as far as predictive tests go.  

All women who give birth are at risk for postpartum depression. At this point, we are not particularly good at reliably predicting which women will go on to develop depression after childbirth.   It is possible to identify women at greater risk – for example, women with a history of a mood or anxiety disorder  or women who have experienced postpartum illness after an earlier pregnancy.  While screening for these groups of women will undoubtedly help us to catch many women who will go on to develop PPD, it will probably miss quite a few vulnerable women.

Rather than waiting for postpartum depression to occur, our goal is to identify women before they give birth who will go on to develop postpartum illness.  If we could do that, we might be able to actually prevent the depression from occurring.  Or at least, we could intervene in some way so that the depression would not significantly affect the mother and her family.

Ruta Nonacs, MD PhD

Chen C, Gao J, Zhang J, Jia L, Yu T, Zheng Y.  Serum leptin level measured 48 h after delivery is associated with development of postpartum depressive symptoms: a 3-month follow-up study.  Arch Womens Ment Health. 2016 Jun 13. [Epub ahead of print]


Related Posts