baby blue

1 :  a pale blue

2 baby blues plural :  blue eyes She's a zaftig woman, with long red hair and a pale rose complexion setting off those baby blues. — Michele Kort

3 baby blues plural in form but singular or plural in construction :  a feeling of sadness that is experienced by a woman shortly after giving birth, that is typically accompanied by other symptoms (such as mood swings and loss of appetite), and that usually lasts less than two weeks Baby blues isn't an illness or even a proper psychiatric diagnosis, it is simply a way that people have tried to describe unpleasant feelings that occur shortly after having a baby and tend to resolve in a few days. — Jackie Ganley —usually used with the a case of the baby blues