Justin Bieber is a big brother once again following the birth Thursday of baby girl Bay Bieber from Justin's father, Jeremy Bieber, and step-mother, Chelsey Bieber. The pop star announced the birth of Bay on Instagram alongside a photo of the newborn wrapped up in a blanket. "Meet the newest bieber, my little sister BAY BIEBER," Bieber said. Jeremy also shared the news about Bay's arrival on Instagram, posting a photo of himself, the baby and Chelsey inside the delivery room. "We welcomed a healthy baby "Bay Bieber" born at 830 am," Jeremy said. Jeremy now has four children from previous relationships including Jazmyn, 10, and Jaxon, 8. Bay is Jeremy's first child with Chelsey, who is also the mother of Allie, 11. Jeremy and Chelsey tied the knot in February during a wedding that was attended by Bieber and his ex, Selena Gomez. In Julu, Bieber confirmed he was engaged to Hailey Baldwin. "You are the love of my life Hailey Baldwin and I wouldn't want to spend it with anybody else," he said at the time.