There's another baby on the way for a former "Teen Mom" star. 21-year-old Mackenzie McKee is pregnant with her third child, and the father is her estranged husband, Josh McKee.

Mackenzie, who is already mom to son Gannon, 4, and daughter Jaxie, 2, is reportedly 18 weeks along with her third. The news that Josh is the father comes as quite the surprise to her fans, since the two are no longer living together, according to TMZ.

The young couple's relationship has had its fair share of ups and downs. The two welcomed their first child together when Mackenzie was just 16, and had their saga documented on the MTV reality show "16 and Pregnant." Their engagement, and subsequent battles over whether or not Josh should continue his work in the rodeo, were all filmed for the third installment of "Teen Mom," entitled "Teen Mom 3."

The pair tied the knot on August 17, 2013, just a few weeks before their season of "Teen Mom 3" started to air. Unfortunately, "Teen Mom 3" was canceled after the first season, and their rocky relationship would not lead to a happily ever after for Mackenzie.

Though Josh and Mackenzie are currently estranged, it isn't the first time they've split. Back in April 2015 the two made headlines with their volatile breakup, when Mackenzie crashed her car into a ditch while out looking for her husband. A fight ensued, and Josh ended up throwing her ring in the toilet and leaving the home they shared together.

Mackenzie made another type of headline a few months later, when TMZ revealed that she was in talks with the adult entertainment company Vivid in July 2015. The company reportedly obtained a sex tape that featured the "Teen Mom 3" star, and then contacted Mackenzie about releasing the video. The reality star never agreed to sign off on the video's release, unlike her fellow "Teen Mom" Farrah Abraham, and kept her sex tape from being distributed.

Despite having a rocky relationship that was chronicled on television, Mackenzie reportedly believes that this time around their breakup is permanent. She is planning on raising the third child as a single mom.