A new mom on Reddit has banned her mother-in-law from being alone with her 4-month-old baby after catching her in a lie that could have endangered the boy's life.

"Since he was born, my mother-in-law has been begging to keep him for an overnight stay to give us a break. I've been hesitant because he is really a very easy baby; we all get plenty of sleep and he makes being a mom easy. She babysits during the day on occasion," she began.

When the couple were recently invited for a night out with friends, they reluctantly agreed to let his grandmother watch him overnight.

"I explained my expectations, the only major one being safe sleep protocol. I told her he must sleep on his back, no exceptions. She didn't have to use the swaddle (she's expressed scorn for them in the past), I sent him with a sleep sack too so she was free to use that if she could get him relaxed enough in it, but he must be on his back. It was my only rule," the mom wrote.

"I've caught her letting him nap on his tummy before, but she's always been directly supervising him, and being a new mom I didn't really want to start anything in those situations. But with a full overnight I was adamant, back sleep only, while she was also sleeping. She agreed to this," she continued.

However, on their way home after their night out, she became uneasy and asked her mother-in-law to send a photo of the sleeping baby.

"She sent me a picture of him laying flat on his belly asleep in the bassinet. Then I think she remembered my rule, because it was followed up hastily with, 'I have to turn him over, he keeps rolling,'" she shared, explaining how she had caught her mother-in-law in a big lie.

"This, dear readers, was a lie. My son isn't rolling yet, we've been practicing daily but he still doesn't have the strength or muscle memory to do it by himself yet ... I turned to my husband and after a quick discussion, we turned around to drive the hour to pick him up at 2AM. On the way, my husband laid into her for lying to us, and by the time we got there she was crying and refused to acknowledge us at all," the mom continued.

She grabbed the baby and his car seat while her mother-in-law threw his diaper bag at her and slammed the door in anger.

"On the way home my husband and talked some more, and I told him that I'd see how our son slept in the sleep sack and if he really did keep rolling while in it, I'd call my mother-in-law the next day and apologize. Once home, I put him to bed and he couldn't even get settled without his swaddle. He was nowhere close to rolling, just flailing his arms around and crying when he whacked himself in the face, since he's not accustomed to having his arms free overnight yet," the mom explained.

"So, she disobeyed my only rule, and put him to bed on his belly, and is angry with us for calling her out for lying about it," she concluded.

READ MORE: Bride-to-Be Refuses to Let Sister Bring Therapy Dog to Wedding

Users in the comments slammed the woman's mother-in-law for not respecting her wishes for her baby.

"She has done it before, her lying about it shows that she puts her way of raising your kids before yours. And what was that, she threw the diaper bag at you? No babysitting for her, not only because she obviously doesn't listen to you but is also lying and angry?!" one person wrote.

"Asking her to put baby to sleep on his back isn’t something you’re just being picky about. It’s literally a fact that back sleeping is the safest for infants under the age of one. I would truthfully never trust her alone with him again and I hate to sound prude. Many people have survivors bias ingrained in them ... 'We did it back then and nobody got hurt' mentality. That mindset is especially dangerous with a baby," another shared.

"You were holding your baby and she threw his diaper bag at you! Never had a child, but if this were my child, MIL wouldn't see him again until after he had received his second or third PhD! The diaper bag could have hit him, caused you to drop him, or hit you. What was she even thinking? Rhetorical question as she had not been thinking the entire evening! She endangered your infant, lied to you about it, and then endangered him again. She does not deserve another chance," someone else commented.

Celebrities Accused of Satanic and Demonic Rituals

Some genuinely believe these music stars sold their souls to the devil in exchange for fame and fortune.

Gallery Credit: Erica Russell

More From KISS FM 96.9