Allowing SO to make decisions during pregnancy

I am 38 weeks pregnant with my first. My SO has two children already from a previous relationship. With that, I look to him for a lot of pregnancy advice. He is also very into my diet and will call me out when I am not eating well for baby. I have no issue with this as this baby I am carrying is just as much his as mine. His mom can't stand that I let him dictate any part of my pregnancy. She claims that I am the only one in control of rearing this baby. While I agree it is my body, I do not see an issue with him taking a strong stance about me having the most healthy pregnancy as possible. What are your thoughts on this? Anyone else have a very involved partner?