On Sunday, the Duke and Duchess of Sussex announced they were expecting their second child months after revealing they suffered a miscarriage in July.
"[They were] hopeful that they would get pregnant again," a source close to the couple told People magazine on Wednesday. "And they were overjoyed that it happened so quickly."
The pal admitted that the couple was "devastated" by the miscarriage.
"They were both nervous, and it took them a while before they could relax and fully enjoy this pregnancy," added the insider. "They always wanted for Archie to have a sibling close in age."
Over the weekend, a spokesperson for Harry, 36, and Markle, 39, told Fox News: "We can confirm that Archie is going to be a big brother. The Duke and Duchess of Sussex are overjoyed to be expecting their second child."
In a black-and-white photo of themselves, the couple sat near a tree with Harry’s hand placed under Markle’s head as she lay on his lap with her hand resting on her bump.
The baby will be eighth in line to the British throne.
The duke told chimpanzee expert Jane Goodall in 2019 that he would only have two children for the sake of the planet.
Goodall, 86, said: "Not too many," and Harry replied: "Two, maximum."
Harry and Markle, a former American actress, married at Windsor Castle in May 2018. Their son Archie was born a year later.
In early 2020, the couple announced they were quitting royal duties and moving to North America, citing what they said were the unbearable intrusions and racist attitudes of the British media. They recently bought a house in Santa Barbara, Calif.
In the op-ed, the former "Suits" star described how she realized something was wrong one July morning while caring for Archie.
"After changing his diaper, I felt a sharp cramp. I dropped to the floor with him in my arms, humming a lullaby to keep us both calm, the cheerful tune a stark contrast to my sense that something was not right," she wrote. "I knew, as I clutched my firstborn child, that I was losing my second."
Markle said she laid in a hospital bed hours later, where she kissed Harry's knuckles that were "wet from both our tears."
"Staring at the cold white walls, my eyes glazed over," Markle shared. "I tried to imagine how we’d heal."
Markle said she was sharing her story to help break the silence around an all-too-common tragedy.
"Losing a child means carrying an almost unbearable grief, experienced by many but talked about by few," she wrote. "Some have bravely shared their stories; they have opened the door, knowing that when one person speaks truth, it gives license for all of us to do the same."
In the Times article, Markle goes on to describe how she tried to keep a "brave face" in the public eye. She recalled a moment last year as she finished up a long tour in South Africa with Harry when a journalist asked her "Are you OK?"
"Thank you for asking," she replied. "Not many people have asked if I’m OK."
Markle deemed the question of "Are you OK?" to be important, especially in 2020, a year she said that has brought "so many of us to our breaking points."
The Associated Press contributed to this report.