Postnatal depression is a type of depression that some women experience after having a baby. Although this depression can develop within weeks after the birth of your child, symptoms don’t often become apparent until months later.Symptoms of postnatal depression are wide ranging: mood changes, irritability, trouble sleeping, thoughts of harming the baby, and episodes of tearfulness are just some of the many symptoms. An added danger of postnatal depression is that mothers who fear they may be suffering from it are usually hesitant to ask for help.