The reality TV star, who is expecting her 19th child with husband Jim Bob, was admitted as a precaution after experiencing "gallbladder issues".
A spokesperson for TLC, which broadcasts the 42-year-old's fly-on-the-wall series, explained: "The pain from a gallstone was generating some contractions. Just to be safe, she was airlifted to a Little Rock, AR hospital, so that in the unlikely event that she had to be delivered early, she would be close to a NICU centre.
"Though there were some fears that the baby was in trouble initially, it soon was discovered to be solely the gallstone causing the discomfort. Michelle is resting comfortably and the baby is doing fine."
The representative added: "Doctors want to observe Michelle in the hospital for the next couple of days, but it would appear that the pain medication they have given her for the gallstone has worked, and there is no need for immediate surgery."
Meanwhile, hospital doctor Curtis Lowery told People that he has "every reason at present to expect that mother and baby will proceed with a healthy pregnancy".
18 Kids and Counting airs on Tuesday nights on TLC.