Could a Blood Test One Day Predict Postpartum Depression?
Too few people get diagnosed and treated for postpartum depression. But a blood test could change that
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Postpartum depression (PPD) affects 10 to 20 percent of birthing parents globally with debilitating effects, including depression, severe mood swings, withdrawal from family and friends, and an inability to bond with their baby. Although a previous major depression diagnosis is a risk factor, many people with PPD have never had any depression symptoms. But new research could help us better understand who is most likely to experience the condition and potentially predict it so that pregnant people can seek treatment before the onset of symptoms.
In the study, published in January in Neuropsychopharmacology, researchers confirmed through a blood draw taken from 136 people between 34 and 36 weeks of pregnancy that women who were later diagnosed with PPD metabolized the sex hormone progesterone differently in their third trimester of pregnancy. Progesterone is derived from cholesterol and has many roles, including influencing gamma-aminobutyric acid (GABA), a neurotransmitter that affects the nervous system and enhances a feeling of well-being. When progesterone is broken down into metabolites, the ratio of these chemicals, known as neurosteroids, can either block or aid GABA’s ability to deliver calming effects.
When GABA receptors are activated, they allow negative ions to flow into the neuron. This makes it more negatively charged, which blocks neuronal activity and has a soothing effect. But when these receptors shunt GABA, they cannot send negative ions through the neuron and dampen the stress response. Study participants who went on to develop PPD tended to have more progesterone in their blood because it wasn’t broken down at all or had a higher proportion of the metabolites that shunt GABA receptors.
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Predicting symptoms of PPD is crucial for a condition that is notoriously underdiagnosed in the U.S. Only around 3 percent of people with PPD are diagnosed, treated and reach remission, says Lauren M. Osborne, the new study’s lead author and the vice chair of clinical research in the department of obstetrics and gynecology and psychiatry at Weill Cornell Medicine. “If we had a blood test that could predict postpartum depression, it would alert clinicians and patients so they could start treatment immediately postpartum in the hospital to prevent the onset of postpartum depression,” she says. The next step will be to replicate the study in a larger and more diverse population to see if the findings hold up. Osborne notes that researchers are still many steps away from producing a cost-effective blood test that could be used as a regular part of prenatal care.
“This is important, as [postpartum] depression is often only recognized at a relatively late stage, and then the long-term consequences for both mother and child are generally more severe,” says Elseline Hoekzema, a neuroscientist who runs the Pregnancy and the Brain Lab at Amsterdam University Medical Center and was not involved in the study. If the condition goes undiagnosed, it can become dire. Suicide is currently a leading cause of maternal mortality in the U.S. It accounts for about 20 percent of postpartum deaths.
Osborne says that the blood test could also be used in conjunction with a relatively new, already-available treatment that uses a similar mechanism to quell symptoms. The medication, called zuranolone, was approved by the U.S. Food and Drug Administration in 2023. It’s a synthetic version of allopregnanolone, a progesterone metabolite that’s been found to enhance GABA functioning in the brain. If a lower progesterone level or higher ratio of allopregnanolone to pregnanolone inhibits GABA and causes postpartum depression, researchers may already have an effective tool for treating those at high risk.
The oral medication hasn’t been tested on pregnant people, so we don’t know if it’s safe for the pregnant person or fetus. But it has been shown to effectively reduce postpartum depression symptoms almost immediately for some people, and it achieves full effectiveness within a two-week course of treatment. This is in contrast with traditional antidepressants such as selective serotonin reuptake inhibitors (SSRIs), which can take months to start working.
But there are caveats. The medication could be problematic for new parents who don’t have help with childcare because the most prominent side effect when the drug is being taken is intense drowsiness and fatigue. New parents taking the drug would benefit from having someone else around who can respond to the baby’s needs during the two-week course of treatment.
Jamie Maguire, a professor of neuroscience at Tufts University School of Medicine, says that the research also points to clues about what could be going wrong in those with PPD. “It not only tells us a potential biomarker that we can use but it also tells us something about the underlying neurobiology of postpartum depression,” says Maguire, who was not involved in the study. She adds that it confirms something that researchers have suggested for years: that the cause of PPD is different from that of major depression, which has been associated with an imbalance of other neurotransmitters in the brain, such as serotonin and dopamine.
The new study’s findings come none too soon for a condition that has long been understudied, lacks treatments and tools, affects half a million people in the U.S. annually and continues to carry undue stigma because so many people suffer silently. “This could be really impactful for patient care,” Maguire says.
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