The photo was meant as a fun and honest moment from a new mother, who previously struggled with infertility, but the comments turned negative.
Kiernan, 42, responded with another Facebook post the next day, quoting one of the comments on her photo and warning those on her page that a "snarky message" was coming.
"'This doesn't even look like the same person!' etc, etc...mean, nasty, hateful comments. Newsflash: These are not pictures of the same person," Kiernan wrote.
"The woman on the left is well rested, spent two hours on her hair and makeup, had a professional photographer take her picture (and photoshop it, I'm sure), and is in the 'glowing' second trimester of pregnancy," the WHO-TV anchor wrote. "The woman on the right got two hours of sleep (maybe), hadn't looked in the mirror, took a selfie, did not put a filter on it and is covered with spit up and drool from a teething and very crabby baby."
"You are an idiot if you think these are pictures of the same woman."
Her post was praised, gaining hundreds of shares and thousands of comments, many from other mothers giving positive feedback.
"I think you look amazing in both pictures," Kelly Carlton wrote in a comment. "Being a new mommy takes its toll and you are doing great holding down a full time job away from home and a full time job at home."
"I love that you are so honest and willing to share that you are a normal person just like the rest of us," Nancy Kelderman said. "You don't pretend to be someone that you are not and you don't hide the fact that your life is not always glamorous."
"Bravo to you for keeping it real," said Katrina Kvesic Dickes.