Early bonding with mom is crucial to a newborn's sense of security. The new world is much less comfortable than the warm, cushy uterus, and mom is the warm, cushy connection to that safe place.
If mom is depressed, that connection is unstable, impacting an infant's early development. A study conducted by Israeli researchers and published in the August 2009 issue of the Journal of the American Academy of Child and Adolescent Psychiatry is one of the latest to look at these impacts. The researchers identified several components of a baby's cognitive response and development that can be affected by a mother's postpartum depression: social engagement, stress level and fear reactivity.
Fear reactivity is a survival instinct. When confronted with something new, an infant reacts with fear in order to protect itself. To interact in a healthy way with the world and the people in it, the baby must overcome that fear response, which can be measured concretely by cortisol levels. Cortisol is the "stress hormone."
The mother is the primary mediator between baby and world in the first year of life. Her own comfort with the world, herself and other people, along with her ability to pick up on and respond to her infant's cues, informs how comfortable her child feels interacting with new people and experiences. It effectively teaches the baby how safe the outside world is. A depressed mom is profoundly uncomfortable with her own life and less intuitive about her child's needs [source: Anderson]. The natural result is an infant who is more fearful and less open to novelty.
Since the earliest interactions between baby and mom and, by extension, baby and world, start to shape a child's social development, PPD's effects on fear reactivity and stress levels early in a baby's life can have long-term effects on social engagement. A U.K. study published in the Journal of Child Psychology and Psychiatry in 1999 found that 5-year-olds whose mothers had been diagnosed with PPD had more behavior problems at home and at school [source: Murray]. There is even evidence that older children may have lower IQs if their mothers were depressed in the first months after delivery [source: Medscape].
This all sounds pretty damning, but it's not as bleak as it sounds. While postpartum depression was not very well-understood 50 (or even 20) years ago, it's now a highly studied, easily recognizable illness. Easily recognizable by mental-health experts, that is. So it's essential for moms to seek professional help early on (from a doctor, psychologist or social worker, typically) when any signs or symptoms of PPD persist beyond the first couple of weeks postpartum. The condition is often treated very successfully with therapy, medication or a combination of the two. Nipping the problem in the bud can help mom and baby avoid the potential cognitive effects of PPD.
For more information on postpartum depression and related topics, look over the links on the next page.