have the baby blues—(coll.) feel sad or depressed when pregnant:
- After seven months, Karly had the baby blues. She was feeling sad.
have the blues—(coll.) feel sad or depressed:
- Doctors told her she just had the blues, and although they offered her medications, they did not keep her in the hospital.
Note: The expression does not correlate in meaning with the phrase have a blue—(Austral. sl.) get into an argument; start a fight or brawl:
- There is an old bloke who sits on the verandah of the pub who won’t drink inside because he had a blue with the publican.