"Baby Vuolo is growing," she wrote on Instagram, adding such hashtags like, "15 weeks" and "baby bump."
The 24-year-old "pregnant mama" is seen posing with a blackboard behind her, with her week-by-week progression and "baby is the size of an apple."
According to Baby Center, a baby is the size of an apple at 15 weeks, and weighs about 2.5 ounces. The baby is about four inches long from top to bottom, with the site noting that at this phase is when the baby's lungs are starting to develop. Additionally, it begins sensing light. By now, the baby can also move its joints and limbs. Next week, Vuolo's baby will be the size of an avocado, weighing 3.5 ounces and measuring 4.5 inches long.
If Vuolo wants, she could even find out the baby's gender from an ultrasound too, Baby Center reports. In November, fans tried to figure it out themselves when husband Jeremy Vuolo posted a photo of the happy couple licking lollipops.
"Sugar and spice. Think about it," Jeremy wrote. That led people to think she is having a girl.
Jeremy also recently updated his bio at Grace Community Church, where he is the pastor that confirmed when their baby is due.
"They are expecting their first child in July of 2018," the bio reads.
That date lines up with Vuolo's Instagram post. There are 37 weeks from today until July 1, 2018, with 39 weeks in nine months.
Vuolo and her husband Jeremy have been married since November 2016 and live in Laredo, Texas. They announced they are expecting their first child in a YouTube video on Jan. 3.
"I am praying that the baby will look like, act like, talk like, be like Jinger, and so I've asked everyone else to pray as well," Jeremy said in the video. "I was a little terror as a child, so I'm hoping that the little one will be as much like Jinger as possible."
"I hope that the baby will be like Jeremy," the former Duggar daughter said. "He's just very kind and gracious."
Vuolo's fans are also happy about their pregnancy. "I am so happy for you and Jeremy. You are going to be wonderful parents," one fan wrote.
"Sooo cute," another fan wrote. "Happy you guys spent a year getting to know marriage now adding to your family God's blessings on you and your family."
Photo credit: Instagram/ Jinger Vuolo