Jessica Simpson is "almost there" with her pregnancy

However, Jessica's younger sister Ashlee, 34, says she is nearing her due date and can't wait for their baby girl to arrive.

According to Us Weekly, Ashlee said: “She’s doing great. Almost there. That ending, you’re like, ‘Okay, I’m ready.'”

Jessica - who also has Maxwell, six, and Ace, five - previously admitted she "doesn't understand" how she got pregnant again.

She admitted: "I thought about [having another baby], but I didn't really know that it could actually happen. We definitely always love to practice. We actually weren't practicing very much that month so I don't understand. We try [to figure it out]. This might be a miracle baby."

And Jessica's children are "so excited" to be a big brother and big sister.

She added: "They're so excited because they're only fourteen months apart, so they didn't get to experience the excitement of each other. But when I told them that we're having another baby, I know that they'll remember that for the rest of their lives. They are most excited about learning how to do the swaddle. Maxwell, my daughter is just so happy that it's a girl. They ask me the craziest questions that I can't say on TV ... 'How does the baby come out?' 'Where does the milk come from, I don't understand!' I'm a little bit too honest, and Eric's like, 'I don't think we need to give out ALL the information, Jessica. So, I'm scaring my kids, I think."

Revealing the sex of their unborn baby in an Instagram reveal post, Jessica wrote: "This little baby girl will make us a family of five. We couldn't be happier to announce this precious blessing of life."