Researchers from Johns Hopkins School of Public Health in Baltimore, Md., looked at height data for more than 6,500 children during pre-school and kindergarten. They found that kids around age four with mothers who reported having mild or moderate depression during their child's infancy were more than 40 percent more likely to have children with short stature compared to mothers who did not report depressive symptoms.
The study suggests that a link between the mother's depression and the child's height persists several years after the mother's reported depression, according to Pamela Surkan, an assistant professor of public health at Johns Hopkins Bloomberg School of Public Health and lead author of the study.
However, for some kids the stunted growth didn't last. The short stature only persisted through age 5 in those with moderate depression, according to the study.
While the study does not indicate when the symptoms of depression began for the women or for how long the symptoms persisted, it's likely that in order for the depression to have affected the child, the mother may have been depressed for months, according to Dr. Kenneth Robbins, clinical professor of psychiatry at the University of Wisconsin School of Medicine, who was not associated with the study.
While the study did not mention what may have caused the link between postpartum depression and stunted grown, Robbins listed a few theories. One reason may be that some children may also be depressed, which can affect the endocrine system and could disrupt the growth hormone, he said.
The study did not confirm that the women were clinically diagnosed with postpartum depression. However, Surkan said it's likely that the numbers may be similar for children whose mothers had a clinical diagnosis.
"There's already very good reasons that mothers who are depressed should seek treatment," said Surkan. "This is one more additional piece of evidence confirming that this is important."
The study also did not track whether the children of even moderately depressed mothers eventually catch up in height after age five.
Nearly 1 out of every 5 mothers in the U.S. has postpartum depression, according to the U.S. Centers for Disease Control and Prevention.
Previous studies suggest that postpartum depression is associated with poor fetal growth, language and cognitive delays, and behavioral problems in children, as well as difficulty in mother-child bonding.
"These children already start with a great disadvantage," said Robbins. "What we're seeing is that there's not simply a psychological effect, there's also a physical effect involved here."
Prevention, early detection, and treatment of a mother's depressive symptoms during the first year after giving birth may also prevent delayed growth as well as other developmental and behavioral problems in children, according to Dr. Deanna Robb, director of the parenting program at Beaumont Hospitals in Royal Oak, Mich.
"Because of research, we've learned so much more and we know the value of early identification to make sure we can identify as soon as possible," said Robb.
In some cases, mothers cannot identify symptoms of depression within themselves, so it is up to physicians to make sure women are properly screened. Even after depression is identified, the diagnosis itself makes it difficult for women to seek help, some experts said. But timely care is essential in protecting the family's health, according to experts.
"The hopelessness of depression often leads people not to seek the care that they need," said Robbins. "If [mothers] can make the connection that this is not just affecting them but also affecting their family, it may become motivation to get the proper treatment."