Oct. 26, 2021 -- New evidence points to the importance of helping mothers with their mental health during pregnancy.
Researchers from the National Institutes of Health in Bethesda, MD, have found that feelings of stress or depression while pregnant are linked to changes in the placenta where the child is growing. The findings, published in Epigenomics, show these changes could alter gene activity.
Stress and depression are not uncommon among expectant women, with depression affecting an estimated 1 in 10 pregnancies, according to the American College of Obstetricians and Gynecologists.
And current evidence already suggests that depression during pregnancy can negatively affect a child later in life. For instance, one study found that depression during pregnancy was linked to behavioral and emotional disorders during childhood, and another found that it raised the risk of depression at age 18.
To investigate stress and depression during pregnancy, the NIH investigators evaluated 301 pregnant women from 12 clinics in the United States who had taken part in an earlier clinical study. The group was ethnically diverse, with 34% identifying as Hispanic, 26% as non-Hispanic white, 24% as non-Hispanic Black, and 17% as Asian or Pacific Islander.
At the start of the study, the women were asked to complete questionnaires routinely used to screen for stress and depression. They completed the questionnaire five more times during their pregnancies. Shortly after each woman gave birth, researchers took tissue samples from the placenta and analyzed the genetics.
The purpose of studying the placenta, according to lead researcher Markos Tesfaye, MD, a post-doctoral fellow at the NIH, is that chemical changes can regulate whether a nearby gene can be activated.
There is evidence that chemical modifications in the placenta can lead to changes in fetal tissues, such as the brain, he says. And the placenta is known for making neurotransmitters, which are needed for fetal brain development.
The team found 16 areas where changes to the exterior of placental DNA were linked to depression in the second or third trimester. They also found two areas where these changes were associated with stress in the third trimester.
"Maternal depression leaves signals in the placenta at genes critical for fetal brain programming," says study author Fasil Tekola-Ayele, PhD, from the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Two of the chemical changes linked to depression were near genes that are known to be involved with fetal brain development and neurological and psychiatric illnesses.
"The findings illustrate that the developing fetus is sensitive to the mother's condition during pregnancy, including maternal symptoms of low mood and perceived stress," says Thalia K. Robakis, MD, from the Women's Mental Health Program at Icahn School of Medicine at Mount Sinai in New York City, who was not involved in the study.
But Robakis cautions that no clinical outcomes were measured among the babies born, meaning that the study could not document any effects of maternal depression and stress on fetal development. Rather, the work contributes to figuring out what mechanisms are involved.
"Pregnant women should continue to focus on optimizing their own physical and mental health," Robakis says. "And they should know that a happy, healthy mother is the most important factor supporting the development of a happy, healthy baby."