What do you call a dead baby in a stroller? A miscarriage.
Why would you joke about a miscarriage.
Calm down, it's only a joke.
Well I don't think it's okay to joke about women having miscarriages. Put yourself in their shoes. I'm sure you could see why your words could be offensive to them.
Why does it offend them?
Carrying a child for many months and imagining what they might be like and then just like that the baby is gone. It seems quite traumatic to me.