Kourtney is expecting her third child with boyfriend Scott Disick, OK! Weekly reported in its latest August 12 issue.
"Kourtney has confessed she's expecting," an insider told OK!. "She's very excited and only telling a select few right now -- but she just couldn't keep it quiet any longer."
The new baby would join the couple's three-year-old son named Mason and one-year-old daughter named Penelope.
A family friend told the magazine, "All the signs are there. Kourtney has that kind of glow she had with Mason and Penelope. Anyway, they wanted to have one right after Penelope."
A recent trip to Miami for the annual Swim Week fashion events apparently had people talking about the Keeping Up with the Kardashians star's apparent baby bump and pregnant-like behavior.
"She didn't drink during the whole trip," the insider said.
For example, Kourtney and Disick attended a runway show at Soho Beach House on July 21.
"They sat in the front row, and while other guests enjoyed their vodka cocktails, Kourtney didn't drink -- but Scott definitely did," added the insider.
Later that night, the pair reportedly partied at PRIME 112, and an eyewitness told OK!, "Kourtney pigged out on desserts and didn't drink, though Scott drank a lot."
The couple also hit Makoto, a popular sushi restaurant, during their stay in Miami. While Kourtney and Disick both apparently love sushi, Kourtney avoided raw fish at all costs.
"Kourtney ate cooked gourmet rolls and a cooked dish [for her main course]. And when discussing the sushi rolls, Kourtney asked the waiter what was in them -- [ensuring] that it was cooked fish inside not raw," the insider explained.
And when a friend asked Kourtney why she wasn't drinking at the restaurant, she and Disick replied it was because she's still breast-feeding. However, when the friend bluntly questioned, "Are you sure she isn't pregnant?" -- the couple changed the subject.
According to OK!, the June 15 birth of North reportedly had Kourtney and Disick reveling at the idea of having another little one of their own.
"When Kourtney first held Nori, a huge look passed between her and Kim, who turned to Scott and joked: 'Uh-oh,'" said the family friend. "Scott knew exactly what she was thinking."
Despite the alleged evidence and speculation Kourtney's pregnant again, according to another family insider, the public won't know for sure until the time is right.
"The tradition is to wait until the second trimester before announcing -- you know, just in case things go wrong," the family insider told the magazine. "I know Kourtney and Scott have been trying. So a baby now makes sense -- it's very easy to get pregnant after giving birth once, let alone twice."