"Great time with family and friends celebrating Marcus' birthday!" the family captioned a slideshow from Marcus' big day, as he posed with his siblings, parents, and grandparents, Jim Bob and Michelle.
Josh and Anna revealed in March that they were expecting baby No. 5, nearly two years after their marriage was rocked by scandal. In 2015, Josh entered a faith-based rehab facility, shortly after it was revealed that he was "unfaithful" to his wife.
"For nearly the last two years, we have quietly worked to save our marriage, focus on our children, and rebuild our lives together as a family," the couple shared at the time. "Doing so is never easy after a breach of trust. We've learned that a life of faith and rebuilding a life together is simply done one day at a time."
"As we continue our journey as a family and rebuild our lives, we are delighted to share with you that we are expecting a new baby boy later this year," they continued. "Beauty comes from ashes and we cannot wait to see and kiss the face of this sweet new boy!"