"The Real Housewives of Potomac" alum Katie Rost is expecting her fourth child. The 38-year-old celebrated in an Instagram post Wednesday after taking a positive pregnancy test. Rost initially shared a photo of a pregnancy test with one solid line and one faint line. She told her followers she was unsure about the results. "Is this one or two lines? I'm confused," she wrote in the caption. "The Real Housewives of Potomac" Season 1 star followed up with a picture of two positive pregnancy tests. "Oh shizzzzzzz, edit, yay!!!!! she wrote. Rost is already parent to son James and twin daughters Renee and Kathryn. She has not shared the identity of her unborn baby's father, although she has been dating a man named Jacob since July. "He kinda loves me a lot #kristinswedding #happywiththeoneilove #dcweddings #KatieandJacob #ChairmanMeow," the star captioned a picture with her beau in October. Rost starred in Season 1 of "The Real Housewives of Potomac" and appeared as a guest in Season 2. She sparked rumors of her return for Season 4 in August after spending time with star Robyn Dixon.