How a mum's text to her husband moments before a crash saved her baby boy.

On Rebecca Tafaro Boyer’s first day back at work from maternity leave, she asked her husband to send her hourly updates and pictures of her baby William.

But when Rebecca received a photo of her son sleeping in his car seat from her husband, she instantly replied with a “nagging mum” text.

Realising her son’s car seatbelt was sitting to low, she quickly messaged her husband, warning him that he wasn’t strapped in properly.

“My nagging wife reply was to correct William’s position in the car seat – the straps were too loose and the chest clip was way too low,” the mum from Memphis recalled on Facebook.

"And because I know my husband, I'm sure that he laughed at me and rolled his eyes before tightening the car seat and fixing the chest clip."

But it turns out Rebecca's nagging text may have saved her son's life.

Just moments after William's father adjusted his car seat, they were involved in a car crash while going 80km/h when another driver made a quick left turn.

While Rebecca's husband suffered injuries to his feet in the crash, William remained asleep during the whole ordeal, safely strapped into his car seat.

"Even with the impact of the two cars, William only received a minor jolt – so insignificant that he was able to continue on with his nap, and then spend the next two hours flirting with nurses in the Le Bonheur ED," Rebecca wrote.

"I am so thankful that my husband took the extra one minute that was necessary to put William in his car seat safely. I can’t even begin to imagine how different the outcome could have been," she added.

"I truly believe that the reason my family is at home sitting on the couch with a pair of crutches instead of down at the hospital is because of my annoying nagging mom voice."

Rebecca's Facebook post about the crash has since been shared over 30,000 times, with Rebecca sharing her advice on how to ensure your child is safely strapped into their car seat.