Researchers studied 875 middle or lower-class mothers in Chile and their healthy children over a 16-year period, evaluating participants roughly every four years.
At any point during the study, about half of the mothers had symptoms of depression, and one-third were severely depressed, according to Patricia East of the University of California San Diego School of Medicine and her colleagues.
At age five, children with severely depressed mothers had an average verbal IQ score of 7.3 (on a scale of 1 to 19), compared to a higher score of 7.8 in children without depressed mothers.
The discrepancy “might not seem like a big difference, but it is truly significant and important and highly meaningful for children’s learning skills,” East told Reuters on phone.
These children will have a smaller vocabulary and poorer comprehension skills, East added.
The study team also found that depressed moms didn’t interact as well with their children, East noted.
Researchers had observed the mothers’ emotional and verbal communication with their children during spontaneous interactions in the home. They observed how often mothers praised their children, read to them, conveyed positive feelings and hugged their child, among other things.
Highly depressed moms were less responsive, affectionate, loving and warm. They didn’t invest emotionally or provide learning materials to their child as much as mothers who were not depressed, the authors write in the journal Child Development.
They found that a mother’s level of emotional, verbal and educational support was more strongly linked with her depression level as children got older.
Michael Schoenbaum, senior advisor for mental health services, epidemiology, and economics at the National Institute of Mental Health in Bethesda, Maryland, told Reuters Health, “I was persuaded before this study that maternal depression has various adverse effects on children over the course of a child’s life in many different ways. This research reinforces that.”
However, he cautioned, the study can’t prove that mothers’ depression was the cause of the children’s problems.
“It’s bad for a child to have a mother with depression and it’s probably surely bad for a mother to have a child who isn’t developing optimally,” Schoenbaum told Reuters by phone.
“I’m not comfortable concluding from their analysis, however carefully it was done, that we know the exact pathways that this happens. But this doesn’t detract from the big picture that maternal depression is something we need to treat,” said Schoenbaum, who was not involved in the study.
The American Academy of Pediatrics (AAP) recommends screening new mothers for depression during the months after childbirth.
“Pediatricians are not only there to monitor children’s health, they’re interested in how well a family is adjusting to a new baby,” said Nerissa Bauer of Indiana University School of Medicine in Indianapolis, who serves on the AAP’s section of developmental behavioral pediatrics.
“We want to make sure we can identify a parent who is not feeling good and has depression as soon as possible to get them the help they need and to support them,” said Bauer. She was not involved in the research.
Among the study’s limitations, the authors note, is that it is based on Chilean women whose parenting style may be different than that of women elsewhere. Also, it did not examine the effect of fathers and extended family on children of depressed mothers.
“I hope if mom is depressed she’ll seek help or intervention so she’ll likely be a better parent and raise a child with higher verbal scores,” said East.