Ludacris’ baby mama is not going down without a fight … she claims he railroaded her in their custody battle by keeping BIG secrets from the judge.

As we reported, Tamika Fuller lost custody of their 1-year-old daughter back in January. She now claims in legal docs she deserves a second bite of the apple because Luda didn’t tell hizzoner his new wife is pregnant and he’s such a bad parent he’s getting a nanny to do the heavy lifting.

It’s a hard argument to make … that a guy who hires a nanny is a bad parent, but she’s trying.

Credit: tmz.com