Babies rapidly grow during the sixth month of pregnancy, and by the end of the month, they should weigh about 2lbs and measure 12-inches from head to heel, according to WebMD.
At 26-weeks, Sarah is halfway through her sixth month, and her baby boy is already where he is supposed to be - although some falsely stated in the comments section that her son's weight was too low.
And while Sarah kept a six-pack throughout her first pregnancy, that hasn't stopped people from speculating about her second - with some accusing her of secretly having a baby via a surrogate, claiming it is impossible to stay that trim while pregnant.
"LOL A surrogate! I've literally heard it all!" Sarah responded to one comment, which has since been deleted. "Are you attending the University of Instagram?"
"Your comment should win a award for being the most entertaining & ridiculous!" she added. "I can also confirm as a mother of a baby who born almost 9lbs that it IS possible ... Anyway, I'm starting to feel really guilty because I'm taking away from your medical "studies"... probably best if you get off Instagram and do more research babes."
Sarah became an online sensation back in 2015 after images of her showing off her washboard abs while nine-months pregnant took the internet by storm.
Although critics insisted her fit physique would negatively affect her baby's health, her son James Hunter weighed over 8lbs at the time of his birth.
Now, more than two years later, Sarah is expecting another boy - and receiving similar criticisms and concerns.
However, that hasn't stopped her from doing what she does best - showing off her incredible figure on Instagram.
Sarah kicked off the workweek by sharing a photo of herself flaunting her toned abs in a tiny maroon bikini, telling her 2.2 million Instagram followers she wants "positive vibes only".
And while it's hard for many people to believe that Sarah has put on any pregnancy weight, she posted a picture of herself showing off her derriere in new jeans, explaining she doesn't fit into her other pairs at the moment.
"Pretty sure some of the 13lbs I've gained has def gone here," she said of her backside.
The soon-to-be mom-of-two announced the news of her pregnancy last month, and she recently decided to celebrate with a nude photo shoot, focusing on her startlingly flat stomach.
"IT'S A BOY!!" she declared on Instagram along with one of the images. "We are so excited!!!! Can't stop smiling!!!"
In revealing the happy news, Sarah explained to Us Weekly that she and her husband, Kris, had struggled to conceive their second baby.
"We had been trying and trying and then every month, I would get my period," she said. "I was getting so frustrated so we decided to take a break. And then it turned out I was pregnant."
he is currently 26 weeks pregnant with her second little boy, and aside from carrying a bit lower and developing a craving for maple donuts, it appears as if Sarah's pregnancy is just as awe-inducing as before.
"Definitely feeling a lot more exhausted this pregnancy," she told Daily Mail Online. "But these pregnancies feel very similar."
And, also like before, she has already been hit with plenty of criticism from keyboard warriors online - despite none of their same concerns being a problem for her last pregnancy.
In response to the hate, Sarah took to Instagram to write: "Taking a moment to thank everyone who has been positive and supportive during this pregnancy, means so much!"
Sarah told Daily Mail Online: "The comments can get draining and part of me feels sorry for those negative people. But the only thing I can do is stay positive and only listen to my doctor who says that baby is measuring perfectly fine!"
