Postpartum depression affects about one in every seven women who give birth, but little is known about what happens in the brains of pregnant women who experience it. A new study begins to shed some light.
Researchers scanned the brains of dozens of women in the weeks before and after childbirth and found that two brain areas involved in the processing and control of emotions increased in size in women who developed symptoms of postpartum depression.
The results, published Wednesday in the journal Science Advances, constitute some of the first evidence that postpartum depression is associated with changes in the brain during pregnancy.
Researchers found that women with symptoms of depression in the first month after giving birth also had increases in the volume of their amygdala, a brain area that plays a key role in emotional processing. Women who rated their childbirth experience as difficult or stressful — a perception that is often associated with postpartum depression — also showed increases in the volume of the hippocampus, a brain area that helps regulate emotions.
“This is really the first step in trying to understand how does the brain change in people who have a normal course of pregnancy and then those who experience perinatal depression, and what can we do about it,” said Dr. Sheila Shanmugan, an assistant professor of psychiatry, obstetrics-gynecology and radiology at the University of Pennsylvania who was not involved in the study.
“The big takeaways are about how there are these really profound brain changes during pregnancy and how now we’re seeing it in depression circuitry specifically,” she said.
The study was conducted in Madrid by a team that has led efforts to document the effects of pregnancy on the brain. It is part of a growing body of research that has found that certain brain networks, especially those involved in social and emotional processing, shrink during pregnancy, possibly undergoing a fine-tuning process in preparation for parenting. Such changes correspond with surges in pregnancy hormones, especially estrogen, and some last at least two years after childbirth, researchers have found.
The new study appears to be the first to scan and compare brain areas during pregnancy and after childbirth and link the changes to postpartum depression, said Elseline Hoekzema, a neuroscientist who heads the Pregnancy and the Brain Lab at Amsterdam University Medical Center and was not involved in the study.
The study authors and other researchers said it was not clear whether the increased volume in the amygdala and hippocampus drove depressive symptoms and perceptions of stress during childbirth or whether the brain changes were occurring in response to the symptoms and stressors. It was also unclear from the brain scans why some women seemed to be more vulnerable to these symptoms than others.
“It might be that those persons whose amygdala is more susceptible to change are also at higher risk of suffering postpartum depression,” said the study’s senior author, Susana Carmona, a neuroscientist who leads the Neuromaternal Laboratory at the Instituto de Investigación Sanitaria Gregorio Marañón in Madrid. “It can also be the other way around,” she said, “that somehow these depression symptoms produce an increase in the amygdala volume.”
The researchers studied 88 pregnant women who had not previously given birth and who did not have previous histories of depression or other neuropsychiatric conditions. For a control group, they also looked at 30 women who were not pregnant. The pregnant women underwent brain scans during their third trimester and about a month after they gave birth.
The women completed standard questionnaires to assess whether they had symptoms of postpartum depression. After childbirth, 15 women showed moderate symptoms of depression and another 13 showed symptoms of depression serious enough to warrant seeking medical help, Dr. Carmona said.
The women also completed questionnaires about whether they perceived their childbirth experience as difficult. Previous studies have shown that “a negative birth experience is associated with increases in depression scores,” Dr. Carmona said. She said difficult childbirth experiences were not necessarily medically challenging deliveries, but could be uncomplicated deliveries that the women perceived as stressful because of factors like rude hospital staff.
Laura Pritschet, a postdoctoral scholar in psychiatry at the University of Pennsylvania who was not involved in the study, called the results “really fascinating,” adding that they point the way to further research “trying to figure out which areas of the brain are changing the most in relation to a variety of outcomes after you give birth, such as mood, anxiety, depression.”
Dr. Pritschet, who wrote an article with Dr. Shanmugan in the same issue of the journal that advocates for research to determine individualized brain signatures of perinatal depression, said the findings of the new study help identify a road map for eventually improving the prediction, diagnosis and treatment of postpartum depression.
“If we routinely show certain brain areas are implicated, what do we do? How can we intervene early?” she said. “What is the normal amount of change? Why might that area be vulnerable? Lots of interesting questions to ask next.”