The 25-year-old was pictured holding Paul in a baby carrier during a family hike, with him facing forward and his legs dangling down.
But fans were quick to comment that Faiers was holding her son "incorrectly", arguing his legs should be in the the 'M' position.
"Having baby face this way puts their legs into an unnatural position and can cause bad hip problems for the baby," one person commented on the photo.
Another person wrote: "Baby should definitely be facing mummy, forward facing means their legs dangle and isn't good for their hips."
"Should try and get an ergonomic carrier," a mother added. "These aren't good for you or baby's legs - the legs should be in the 'M' shape."
However other mums came to Faiers' defence in comments on the photo, slamming those criticising her.
"So many judgemental and unnecessary advice on this photo," someone commented.
"Let people parent how they want to. She doesn't need to know everyone else opinions on how to carry her baby."
Another wrote: "He is her baby, if she wants him facing forward/backwards who cares.
"The choice of carrier/sling/wrap is totally down to the person wearing. As long as she feels comfortable and baby is happy, which he looks, then that's fine."
The National Childbirth Trust advises on its website: "Carrying a baby facing out is not recommended, as it forces your baby’s back straight against your chest, and causes their legs to dangle in a harness like position.
"This can mean the baby’s weight rests on his crotch rather than being spread from his bottom and thighs.
"Allow your baby to assume a position known as spread squat, or M position, where their bottom sits lower than their knees."
In July 2015, new dad Ryan Reynolds also came under fire for the way he carried his baby.
He was pictured with his daughter James facing towards him with her legs dangling down.
Comments began trickling in after the photo was posted, with people concerned about James having her legs dangling down.
At the time, Rosemary Dodd, senior policy adviser at The National Childbirth Trust (NCT) told The Huffington Post UK: "It's recommended, particularly by those concerned with hip dysplasia which is the dislocation of hips, that babies are carried with their legs in the "M" position.
"Carrying a baby close to you is a good idea when they are small because they settle more easily, so we would praise him for that.
"But the concern is that it is just more comfortable and better for the baby to use the 'M' position."