Low Levels of Anti-Anxiety Hormone Linked to Postpartum Depression
BALTIMORE, Md -- March14, 2017 -- In a small-scale study of women with previously diagnosed mood disorders, researchers report that lower levels of the hormone allopregnanolone in the second trimester of pregnancy were associated with an increased chance of developing postpartum depression in women already known to be at risk for the disorder.
In a report on the study, published online in Psychoneuroendocrinology, the researchers say the findings could lead to diagnostic markers and preventive strategies for the condition, which strikes an estimated 15 to 20% of women in the United States who give birth.
The researchers caution that theirs was an observational study in women already diagnosed with a mood disorder and/or taking antidepressants or mood stabilisers, and does not establish cause and effect between the progesterone metabolite and postpartum depression. But it does, they say, add to evidence that hormonal disruptions during pregnancy point to opportunities for intervention.
Postpartum depression affects early bonding between the mother and child. Untreated, it has potentially devastating and even lethal consequences for both. Infants of women with the disorder may be neglected and have trouble eating, sleeping and developing normally, and an estimated 20% of postpartum maternal deaths are thought to be due to suicide, according to the National Institute of Mental Health.
“Many earlier studies haven’t shown postpartum depression to be tied to actual levels of pregnancy hormones, but rather to an individual’s vulnerability to fluctuations in these hormones, and they didn’t identify any concrete way to tell whether a woman would develop postpartum depression,” says Lauren M. Osborne, MD, Johns Hopkins University School of Medicine, Baltimore, Maryland. “For our study, we looked at a high-risk population of women already diagnosed with mood disorders and asked what might be making them more susceptible.”
For the study, 60 pregnant women between the ages of 18 and 45 were recruited by investigators at study sites at The Johns Hopkins University and the University of North Carolina at Chapel Hill. About 70% were white and 21.5% were African-American. All women had been previously diagnosed with a mood disorder, such as major depression or bipolar disorder. Almost a third had been previously hospitalised due to complications from their mood disorder, and 73% had more than 1 mental illness.
During the study, 76% of the participants used psychiatric medications, including antidepressants or mood stabilisers, and about 75% of the participants were depressed at some point during the investigation, either during the pregnancy or shortly thereafter.
During the second trimester (about 20 weeks pregnant) and the third trimester (about 34 weeks pregnant), each participant took a mood test and gave 40 millilitres of blood. Forty participants participated in the second-trimester data collection, and 19 of these women, or 47.5%, developed postpartum depression at 1 or 3 months postpartum. The participants were assessed and diagnosed by a clinician using criteria from the Diagnostic and Statistical Manual of Mental Disorders, version IV for a major depressive episode.
Of the 58 women who participated in the third-trimester data collection, 25 of those women, or 43.1%, developed postpartum depression. Thirty-eight women participated in both trimester data collections.
Using the blood samples, the researchers measured the blood levels of progesterone and allopregnanolone, a byproduct made from the breakdown of progesterone and known for its calming, anti-anxiety effects.
The researchers found no relationship between progesterone levels in the second or third trimesters and the likelihood of developing postpartum depression. They also found no link between the third-trimester levels of allopregnanolone and postpartum depression. However, they did notice a link between postpartum depression and diminished levels of allopregnanolone levels in the second trimester.
For example, according to the study data, a woman with an allopregnanolone level of 7.5 nanograms per millilitre had a 1.5% chance of developing postpartum depression. At half that level of hormone (about 3.75 nanograms per millilitre), a mother had a 33% likelihood of developing the disorder. For every additional nanogram per millilitre increase in allopregnanolone, the risk of developing postpartum depression dropped by 63%.
“Every woman has high levels of certain hormones, including allopregnanolone, at the end of pregnancy, so we decided to look earlier in the pregnancy to see if we could tease apart small differences in hormone levels that might more accurately predict postpartum depression later,” says Dr. Osborne. She says that many earlier studies on postpartum depression focused on a less ill population, often excluding women whose symptoms were serious enough to warrant psychiatric medication, making it difficult to detect trends in those women most at risk.
Because the study data suggest that higher levels of allopregnanolone in the second trimester seem to protect against postpartum depression, Dr. Osborne says in the future, her group hopes to study whether allopregnanolone can be used in women at risk to prevent postpartum depression.
She also cautions that additional and larger studies are needed to determine whether women without mood disorders show the same patterns of allopregnanolone levels linked to postpartum depression risk.
If those future studies confirm a similar impact, Dr. Osborne says, then tests for low levels of allopregnanolone in the second trimester could be used as a biomarker to predict those mothers who are at risk of developing postpartum depression.
SOURCE: Johns Hopkins Medicine