Jeff is absolutely right about "birthday". First of all, you enter this physical realm when those 2 cells meet. That is the first miracle hardly anyone talks about. Then comes the transformation into a new being, whose heart is beating and audible 20 something days later. And after that, 8 months of a continuous growth in a liquid environment. Nobody celebrates that. Why? Why only the passage from waters to air counts? Of course it is a tough test, and doing it successfully is a good reason to celebrate. But then we start a ritual, repeated every 12 months, in which we declare to be happy about getting 1 year closer to death. It turns a funeral, especially with those candles.
And there´s more to it. The word "placenta" comes from greek and means "flat cake". What a coincidence! Not. They will tell you that it´s just being thankful to the thing that fed you during pregnancy. It´s fine for a few years. But it becomes a symbol of dependency. An eternal baby that needs to be taken care of. Probably that is why some people get offended if you dare to forget their "birthday".