Young children whose mothers have long-lasting postpartum depression do not seem to suffer any ill effects on their growth and weight gain, new research suggests.

In theory, mothers’ depression, particularly if it’s lasting, could impair babies’ and young children’s growth - by, for instance, making it harder for new moms to breast feed or, at later ages, making sure their children have a healthy diet.

To investigate the question, Brazilian researchers followed nearly 3,800 children and their mothers over the children’s first four years of life. They found that 30 percent of the mothers screened positive for postpartum depression at some point - including nearly 5 percent who persistently had symptoms during the study period.

Initially, children whose mothers had lasting depression appeared to have heightened risks of both stunted growth - shorter than the norm for their age - and being underweight.

Six percent of children whose mothers had long-term depression showed stunted growth, versus 3 percent of children whose mothers were never depressed after giving birth. The corresponding rates for underweight were nearly 4 percent and 1 percent, respectively.

However, after the researchers accounted for factors such as family income and mothers’ education, postpartum depression itself was no longer linked to children’s growth.

Dr. Ina S. Santos and colleagues at the Federal University of Pelotas report the findings in the Journal of Pediatrics.

The results, the researchers write, suggest that while poorer growth was more common among children of chronically depressed mothers, the problem stems from factors other than the depression.

However, they also point out that this may not be universally true.

Studies in India and Pakistan, for example, have linked mothers’ depression to impaired child growth. It’s possible, Santos and her colleagues write, that in some countries where women “face great adversities and are less empowered,” depression may make it difficult for a mother to ensure her children are well-nourished.

The findings also highlight just how common postpartum depression is, the researchers write, with 30 percent of mothers in this study screening positive at some point during their children’s first four years.

That high prevalence, Santos and her colleagues write, suggests that “healthcare workers need to be prepared to screen and recognize maternal depression and treat it appropriately.”

SOURCE: Journal of Pediatrics, online April 19, 2010.