This time isn't as bad but when I was pregnant with DD (the first grandchild and only girl) I had to hear the natural L&D story with tearing from front to back with both boys so many times I wanted to scratch my eyes out. And she seemed disappointed when I told her I had an epidural, like I was a failure or something. And then after she was born, it only got worse. DD hated wearing socks/blankets, so we didn't put them on her- and every time my MIL would hold her she would go walk around and sneak into the nursery and come back with socks on her feet and a blanket, or she would wrap the burp cloth around her feet. And she NEVER put her down, she would rock her to sleep, and then hold her the entire time which I was adamant about putting her down to sleep so she wouldn't depend on rocking to stay asleep.
I love my MIL, and I am very fortunate to have such great in-laws. They help out SO much with DD, and I'm sure it will be the same way with DS. But my mom went through the same thing with her MIL, and I think it's partially because we (my mom and then myself) were raised to be independent and in control. I want things my way, this is how it will be. I don't do well when people deviate from my plans, especially when it has to do with MY child. I'm learning to cope a little more...
Unless you want to strain the relationship, you deal with it. You can listen to her but do what you please. If it gets too bad say something to your DH and let him address it. If we've had issues, I say something to DH, who says something to his dad who in turn filters it to my MIL in a way he knows will least hurt her feelings.
DD is in a Montessori program which my MIL is totally for. The school goes through 6th grade, but we were originally planning on switching her to public school at 1st grade (and now with this LO on the way, she'll make her way over for Kindergarten). I told my MIL (who is a teacher) this and she made some comment about if there's anyway she can stay in private school that's better- my response "are you offering to pay?"