Pregnant Beyonce -- My Fetus and I WILL Honor MJ

Beyonce isn't going to let a little thing like a FETUS get in the way of her October 8 MJ Tribute Concert gig -- TMZ has learned ... the mom-to-be still plans to bust out a song and dance for the King of Pop's tribute show.

Reps for the concert confirmed -- Beyonce is still slated to sing via satellite -- saying the "pregnancy will not affect her performance".

Beyonce is rumored to be nearing the 4 month mark in her pregnancy -- and if the rumors are true, she'll be a solid 5 months preggo when she performs her favorite Jackson 5 song for the concert.

Fun Preggo Fact: According to WebMD, women who were physically active before pregnancy should be good to continue with moderate exercise for the duration of the pregnancy ... as long as any potential "abdominal trauma" is avoided.