"Sister Wives" Robyn Pregnant
“Sister Wives” star Robyn Brown (left), appearing with family members (from second left to right) Janelle, Kody, Christine and Meri, revealed she recently passed her due date. TLC

Baby Brown is running a little late. The arrival of Robyn and Kody Brown’s second child together has been delayed, with the “Sister Wives” star confirming through Twitter she passed her due date.

“Hmmmm ... due date came and went,” Robyn, who was expected to deliver Kody’s 18th child Thursday, wrote in a tweet. “When is this little girl going to come?”

Kody’s fourth sister wife has been sitting on the edge of her seat, waiting for the child to be born. Two days before Robyn’s original due date, she revealed she was excited to see her daughter’s “sweet face.”

Robyn and Kody first announced they were expecting their plural brood to grow in June. “We are so happy to announce an eagerly expected new member of the Brown family!” the duo told People magazine.

The couple, who have four children together (three being from Robyn’s previous relationship), unveiled the gender of their baby during Season 6 of the hit TLC reality-television show, an episode that took place while the Brown family was on an Alaska vacation. During the installment, Robyn and Kody had the family’s two youngest members, Solomon and Truely, unwrap gifts that exposed whether Robyn was having a girl or a boy.

“It’s a girl!” Truely, the youngest daughter of Kody and his third sister wife Christine, shouted after pulling a pink doll from the box.

The family is expected to welcome Kody’s 11th daughter any day now.