Newlyweds Jill Duggar and Derick Dillard celebrated their 19^th week of pregnancy with a commemorative photo on Derick's Instagram account.

The couple have consistently documented Jill's growing baby bump on social media, and are eagerly awaiting the arrival of their baby boy.

The most recent photo features Jill in a long, red and black striped babydoll dress, holding a sign reading "19 weeks." The last baby bump photo the couple shared was at 13 weeks and one day of pregnancy.

The soon-to-be-parents announced last week that they are having a son.

"I was really excited," Derick, 25, told PEOPLE. "As a new dad, to have a firstborn son to be our first child and be the leader of his siblings, it is very special."

Jill also brought three of her 18 siblings with her to find out the baby's gender.

"Oh yes, there was some screaming in the room," the 23-year-old said. "I thought all along we were having a girl. Everyone made their guesses."

Although the "19 Kids & Counting" family members weighed in on what they thought the gender would be, the couple is just praying for a healthy child.

"I was praying for a big, healthy baby," Derick said before the ultrasound. "And Jill added, 'Just healthy, healthy.'"

Jill's parents, Michelle and Jim Bob, chose to begin all of their children's names with the letter "J," and oldest son Josh's three children have names that begin with the letter "M." Jill and Derick may start a new tradition.

"We are not going to do a letter theme," Jill said. "But we may do some kind of theme, like family names."

The Duggar family will soon celebrate the wedding of 21-year-old Jessa to Ben Seewald, a 19-year-old college student. Jessa and Ben will marry on Nov. 1 at the First Baptist Church in Bentonville, Arkansas.