'16 & Pregnant' Star Whitney Purvis Arrested for Not Paying Child Support

"16 and Pregnant" star Whitney Purvis is behind bars again ... after a judge found she failed to pony up for child support payments.

New documents obtained by TMZ show ... Whitney's arrest was ordered Tuesday by a Floyd County, GA judge who found her in contempt of court over failing to pay her ordered child support.

We've learned Whitney has since been booked and is currently in custody -- where she has been ordered to serve 48 hours in jail.

The MTV personality was also hit with some financial repercussions ... as she was ordered to pay an additional $20/per month to cover the back support while still paying her current monthly obligation of $353/per month.

This isn't Whitney's first run-in with the law ... she was also arrested back in 2012 after allegedly shoplifting a pregnancy test from a Walmart.

She got busted again, later that year, when she and then-boyfriend Weston Gosa were accused of destroying someone else's laptop and cell phone.

Whitney's also been booked for allegedly attacking Weston with a broom, and also for allegedly making threats against her ex.

Whitney is best known for appearing on season 1 of "16 and Pregnant," alongside Maci Bookout, Amber Portwood, Farrah Abraham and Catelynn Lowell.

Whitney welcomed her first child, Weston Jr., on the show ... later becoming a mom of 2 in 2014 when she gave birth to son, River. Weston currently has custody of their 2 boys.