Chontel Duncan, a 27-year-old personal trainer who gave birth to Jeremiah on 25 March 2016, concerned fans on Instagram with a photo of her son at 13 days old, in which she didn't appear to be supporting his head.
"I'm concerned about how you're holding the baby," one person commented on the photo.
Another person commented on the photo: "Omg that baby's poor neck.
"Hold your child properly. More important than a selfie."
A few people came to Duncan's defence, arguing there was no issue with how she was holding Jeremiah.
"It's perfectly fine," commenting one Instagram user.
"Supporting the baby's head is a myth, my doctor and nurses supported not holding the head and I'm so glad I didn't, my daughter was stronger than ever."
Another wrote: "Did you ever wonder maybe the baby lifted his head up? Babies do that."
After reading the negative comments, Duncan reposted the snap alongside a photo of her son's head laying against her chest.
"As explained earlier Miah lifted his head up and for that second that he did so, I just happened to have caught it on camera, before he then laid his head back down on my chest," she wrote.
"Newborns can lift their own heads up it's not me standing there with his head flicked back shooting away.
"So have faith people and if you honestly don't like my page just unfollow."
Duncan's second photo received positive comments agreeing with her.
"Newborns are able to lift their head from birth," someone wrote. "I have had four babies, I should know. So many losers out there."
But she does believe the baby's head is "too far back".
Gilchrist said in the photo, there is "no way" the baby will be able to move his head back to neutral position and the position may also reduce air through the windpipe.
"Newborns have very little strength in their necks and require their heads to be supported to prevent rapid forward and backwards motion caused by lack of support," she told The Huffington Post UK.
"Their heads being in an abnormal position could cause their windpipe to close over essentially causing baby to stop breathing.
"I would say it's not about 'protecting their heads' it's about making sure that their heads aren't left to: a) flop into a position where the windpipe is unable to deliver air to the baby's lungs and b) rock backwards and forwards sharply, which may cause injuries to the blood vessels in the brain."
Duncan shot to fame on social media after sharing photos of her bump with "visible abs" during her pregnancy.