"The next Dillard baby is a boy," Derick announced in a video posted to TLC's website. "Israel didn't really understand what was happening but he's just excited because other people are excited, so he's just excited about his new little baby brother."
"We're really excited about having another son," Jill chimed in. "I know that Israel and this little one will be best friends."
The 25-year-old Counting On star also gave fans an update on how her pregnancy is going. "Our pregnancy so far, I had morning sickness in the first trimester and now I'm feeling a lot better in my second trimester," she shared. "Thank y'all for your well-wishes. We're so excited about this new blessing from God."
The couple announced they were expecting another child last month, and were confident that their son would make a great older sibling. "Israel is gonna be a great big brother," Jill declared. "He already loves, like, other little babies, and the only thing I think he's gonna have to work on is learning that babies that are smaller than you, you have to be more gentle with."
Israel is also going to have a new cousin pretty soon. In August, Jill's younger sister, Jessa, also announced that she was expecting her second child with husband Ben Seewald. Jessa, 24, welcomed her son, Spurgeon, in November 2015.
Counting On airs Mondays at 9 p.m. ET on TLC.