Postpartum depression not only takes a toll on moms but also may have a direct impact on their children, a new study finds.

Kids whose mothers said they experienced even mild depressive symptoms nine months after giving birth had a 40 percent higher chance of falling below the 10th percentile in height at age 4.

"Physical growth is one of the most important indicators of early childhood health and has long-term consequences for well-being," study author Pamela J. Surkan, an assistant professor at Johns Hopkins Bloomberg School of Public Health in Baltimore, told The Huffington Post. For example, short stature has been linked to lower educational performance and greater risk of disease, she said.

In the new study, published online in the journal Pediatrics, the Johns Hopkins researchers looked at data on some 6,550 kindergarten-age children and their mothers. At nine months postpartum, nearly one-quarter of the mothers said they had mild depressive symptoms, and another 17 percent said they had moderate to severe symptoms.

At age 4, children whose moms reported having had either mild or more serious postpartum depression had a 40 percent higher chance of being below the 10th percentile in height for their age compared to children whose moms reported no postpartum depression.

At age 5, the association persisted, but only among kids whose moms had had more serious depressive symptoms. These children had nearly a 50 percent higher chance of being below the 10th percentile in height.

Previous research has linked maternal depression to behaviors that can hamper growth such as bad feeding practices and shorter duration of breastfeeding, the Hopkins researchers wrote. Studies have also linked mothers' depression to elevated levels of the stress hormone cortisol and lower levels of the growth hormone in children, both of which may affect height.

"When we talk about the link between maternal depressive symptoms and child growth, we are basically hypothesizing that it is through caregiving," Surkan told The Huffington Post.

"Mothers with depressive symptoms have more limited ability to follow through on caregiving tasks," she hypothesized, cautioning, however, that research on the topic is limited. "Or they may have a reduced ability to seek care for children when they are sick, which, if this happens with a child who is repeatedly ill, could result in shorter stature over time."

In the U.S., between 11 and 18 percent of women say they have experienced regular postpartum depression, according to the Centers for Disease Control and Prevention. Those women may find it difficult to care for their babies and to handle day-to-day tasks. Postpartum depression can be treated through counseling or antidepressants. Left untreated, it may last for a year or more, the Mayo Clinic explains.

But the women in the new study who reported depressive symptoms did not necessarily meet the criteria for a clinical diagnosis of depression. Surkan said that point is important because it suggests that even children whose mothers did not meet the "more stringent" definition of full-blown postpartum depression may see effects in terms of early childhood height.

"This [study] provides yet another reason why women suffering with symptoms of depression should be discussing treatments in consultation with their doctors in their first year postpartum," she said.