Dwight Howard's Ex -- Our Custody Judge Has a Baby Mama Bias!

The mother of NBA star Dwight Howard's son wants the judge in their custody case removed stat ... because she claims he has it out for women who have children out of wedlock with NBA stars.

Royce Reed is battling Dwight in court in an effort to retain primary custody of their son. Dwight filed docs earlier this month to try and wrangle custody from her ... claiming she interferes with his relationship with their son and makes it difficult for him to see the boy on his scheduled days.

The "Basketball Wives" star came back this week with a motion of her own ... to have Judge Tim Shea taken off the case. She claims he has a bias against baby mamas and she fears he may side with Dwight because he's a local celebrity.

In her filing, Reed claims Shea wouldn't let her present her side during a court hearing last month. Reed's lawyer also filed an affidavit saying that during the hearing, Judge Shea said he would award Howard custody, then decided to delay his decision ... despite the fact no evidence had been presented.

Reed also claims there might be a conflict of interest since Shea's own website lists one of Howard's lawyers, Mayanne Downs, as one of his endorsers (see below).

Reed pleads in the docs, "I am afraid if Judge Shea continues to preside over this case, I will lose custody of my son."