My mother-in-law insists on putting a pillow under my 7 month old's head when he sleeps?

She was telling me about how this helped him fall asleep in her arms, when she had a pillow under his head. (She watches him during the day while we are at work.) I guess I didn't realize that he actually SLEPT with the pillow under his head while he was napping. I talked to my husband about it, because the... show more She was telling me about how this helped him fall asleep in her arms, when she had a pillow under his head. (She watches him during the day while we are at work.) I guess I didn't realize that he actually SLEPT with the pillow under his head while he was napping. I talked to my husband about it, because the issue with pillows and SIDS concerns me. He told me, "Well when I was a baby, you weren't even supposed to have babies sleep on their backs. He will be fine." However, I have read that even though a baby can move around fully, he can still suffocate. The recommended age for introducing a pillow is 18-24 months. I've told this to both my husband and my mother-in-law. No one will listen. I can't quit my job to stay home with him to ensure he is getting the care I want him to get, so what is some advice?
Update: Everyone who says, "very simple...just tell her not to so it" has never dealt with a MIL apparently.
Update 2: Not everyone HAS the choice to stay at home. If we want a place to live and food without having to sponge off the government we need a double income. IT is VERY rare in this economy to be able to have a single income. I just want advice on the question I ASKED. NOT TO CRITIQUE MY CHOICES.
13 answers 13