According to The New York Post, the 32-year-old reality star feared a miscarriage and "rushed to her doctor in tears."
After the doctor assured Kim that the miscarriage scare was a false alarm, he warned her about working and exercising too much during her pregnancy.
"She's been working a lot and with the divorce, moving, etc., [she] just needs to take a little rest," a source told E! Online.
Though there's no word yet from Kim's camp, Khloe Kardashian updated fans on her sister's progress via her blog.
"A lot of you have expressed concern in the recent hours about Kim, and I just wanted to let you all know that mommy and baby are doing fine and just taking it easy right now. Thank you so much to all of our wonderful fans and loved ones for your concern and support. We love you!"
Kardashian and West had traveled to Paris for a Givenchy fashion show and a dinner with Frank Ocean and designer Riccardo Tisci.