Every person is different. Every child is different. Stop comparing everyone.
When Mom sighs that she hasn't slept in 3 days because Baby wants to wake up every hour she does NOT need to hear about your friend's child that slept through the night at 2 weeks. She doesn't need to hear that So-And-So's kid started walking/talking/doing calculus straight out of the womb. We're stressed enough when it comes to wondering if our kids are normal. Stop it.
2. Feeding Choices
Now, I'm very pro breastfeeding. I will argue the merits of breastfeeding and support nursing in public with total strangers.
However, there is a time and place for this.
When Mom pulls out a bottle of formula to feed her 6 month old she doesn't need your "breast is best" comments or to get asked why she's not nursing. She has her reasons. She may have tried and it didn't work out. Unless she laments being unable to nurse and ASKS for your advice? Shut up.
On the flip side, if Mom is having trouble nursing but is committed to making it work she doesn't want to hear how Susie's little Snowflake Princess was on formula and is now a doctor or whatever.
3. Feeding Choices 2
The "shut up about food" doesn't stop when the child gets older. I don't care if Mom never lets her child eat foods that start with "D" because Devil starts with "D" and she doesn't support Satan. Don't comment about it. You can roll your eyes behind her back. You can comment on it after she's gone. But when she's standing in front of you your job is to smile, nod, AND FOLLOW THE RULES.
My oldest can't have high fructose corn syrup or food dye. 2 sips of a Gatorade turn him into a crazy demon child (which also starts with D) For someone whose child CAN eat those things without issue? I look crazy. I've stopped caring. Don't feed my kid crap.
My kids don't watch Spongebob. For some reason this stupid yellow thing is considered classic kid stuff. I hate him. He annoys me and studies have linked it with an increase in ADHD behavior. There are a dozen other things that my kids watch. But the looks I get for refusing Spongebob? It's crazy.
My kids also don't say certain things. Shut up, stupid, hate, and moron come to mind first. If YOU say it around them they'll correct you. Don't shoot me an annoyed look. Laugh it off and move on. They're just kids.
5. Keep your "but" to yourself
Oddly enough, this is a general rule for my household!
If your sentence has a 'but' in the middle of it I probably don't want to hear it.
I support nursing in public but...only if mom is covered.
Breastfeeding is great but...there's nothing wrong with formula.
That's cool that your son is intact but...isn't it weird?
I'm all for natural birth but...
He's so sweet but...