The results of a large study do not support the notion that prenatal and postpartum maternal depression is particularly detrimental to children's psychological development. Instead, the most robust effects were found for maternal depression occurring during children's preschool years.

The analysis examined 11,599 families including 17,830 siblings from the Norwegian Mother and Child Cohort study. Using sibling comparisons, investigators accounted for genetic and shared environmental factors, as siblings share family environments and their mothers' genetic risk for depression.

After taking familial factors into account, the researchers found that only concurrent maternal depressive symptoms had an effect on emotional and behavioral problems in preschool-aged children.

"We found that children of mothers who were depressed before and after birth had more mental health problems because they share risk genes with their mother; however, spending time with a depressed mother in the preschool years can be harmful to the child's mental health," said Dr. Line C. Gjerde, lead author of the Journal of Child Psychology and Psychiatry study. "It is therefore important to reach these mothers as early as possible, and provide treatment."

Article: Maternal perinatal and concurrent depressive symptoms and child behavior problems: a sibling comparison study, Line C. Gjerde, Espen Moen Eilertsen, Ted Reichborn-Kjennerud, Tom A. McAdams, Henrik Daae Zachrisson, Imac Maria Zambrana, Espen Røysamb, Kenneth S.. Kendler and Eivind Ystrom, Journal of Child Psychology and Psychiatry, doi: 10.1111/jcpp.12704, published online 23 February 2017.