On April 13, 2009, Josh and Anna Duggar announced that they were expecting their first child. As Josh was the only married child of Jim Bob Duggar and Michelle Duggar at the time, this announcement was noteworthy as the child would be the first grandchild for the couple, whose family was the subject of the reality show 18 Kids and Counting. Josh shared his excitement, saying "I am very excited and am learning new ways every day that I can be there for my wife".
On May 12, 2009, TLC aired the 18 Kids and Counting episode "Duggars on a Double Date", which showed the couple learning of their pregnancy and sharing the news with their family. In the episode, Anna takes a pregnancy test (like she had many times previously in her few months of marriage) and leaves it for Josh to look at the results, saying she didn't want to be disappointed again. Upon finding the test was positive, Josh shared the news with Anna by saying: "You're going to join the mommy team!". After calling Anna's family to tell them the news, the couple visited Josh's family to share their excitement. "We are so thrilled about this news," excited grandmother-to-be Michelle said, "It is so fun to be around Josh and Anna. They are walking on clouds.". "We are really excited about being grandparents," grandfather-to-be Jim Bob Duggar added on. "We think it is really going to be easier than being parents.".
On June 15, 2009, Josh and Anna appeared on the Today Show, where they cut into a cake to learn the gender of their first child. When they cut into the cake, they learned, along with America, that they would be having a girl. Josh spoke on the show about his experiences preparing to be a father, saying, "I think you can prepare only in so many ways, but really just realizing that you're going to be a role model for that child, and be able to be prepared as you can be to be able to take on that. It's an interesting experience, but I have great parents to look to.". Josh also said that he'd be happy with a small family: "We'd be happy with two or three; I think children are a blessing though, so we're just thankful for the one that God has given us, and we'll take 'em one at a time.". This gender reveal is featured on the 18 Kids and Counting episode "Oh Duggar Baby! It's a...", which aired on June 30, 2009.
On July 31, 2009, Josh and Anna announced via People Magazine that they had chosen a name for their daughter: Mackynzie Renée Duggar. "We won't decide that now," Josh said when asked if all of their children would have names that began with the letter M, a tradition his parents kept with the letter J. "We'll take one at a time.". "My favorite part of pregnancy is feeling the baby move and kick," Anna said in the interview. "And, it is so neat watching Josh enjoy the pregnancy and bond with Mackynzie. It had brought our relationship closer together.".
On September 1, 2009, Jim Bob and Michelle announced that they were expecting again. The baby, who would be the couple's nineteenth child, was due to be born after their first grandchild. "My sister and my mother were having babies at the same time, so I have nieces and nephews older than me," Michelle said when asked about this. "It was a great time because we really have close relationships with my nieces and nephews.".
On October 9, 2009, Josh and Anna announced via People Magazine that they had given birth to Mackynzie. In the announcement, they revealed that the newborn was named for a cousin of Josh's and that she shared Anna's middle name. At birth, Mackynzie weighed 8 pounds and was 19 ½ inches long.
On October 13, 2009, TLC aired the 18 Kids and Counting episode "First GrandDuggar!", which centered on Mackynzie's birth. In the episode, viewers learned that Anna had planned on delivering in a hospital, but when she learned her doctor, Dr. Amy Sarver, was out of town, she and Josh made the decision to deliver at home instead. The birth was assisted by a midwife and a doula, as well as Michelle and Josh's eighteen-year-old sister Jill.
She was a flower girl at her father's cousin Amy's wedding to Dillon King on September 6, 2015.