The baby blues are a common type of depression, and it is the least severe of postnatal illness. It is thought that half of new mothers will experience the blues.
It does not usually last very long - possibly just hours, starting from around the third day after birth and lasting no longer than the tenth day. It is mostly due to the enormous physical, hormonal and emotional changes your body goes through as you adapt to a non-pregnant state. During this time, you may feel tearful and irritable, but no medical treatment is needed.
If the blues do continue and seem to be getting worse then the mother should see her GP to discuss the problem.