Q: What do I need to do to get a birth certificate?
Be born.
Q: I was hatched, spawned or asexually produced. Can I get one?
No, birth only.
Q: How about a Caesarian birth?
Totally okay. You can get a regular birth certificate.
Q: What if I sprung out from my father's head, fully adult, with arms and armor?
No birth certificate for you.
Q: I am a fictional character, but my fictional origin includes birth. Can I get a birth certificate?
You can get a forged birth certificate, but not a real one.
Q: I am a sixteen word question within an FAQ list; can I get a birth certificate?
Of course not. But you do get an answer. I'm assuming FAQ counts as one word.
Q: How about in vitro fertilization?
That's fine. You still count as being born.
Q: Who makes these rules anyway?
Various nations and governments.
Q: Well, I am a government unto myself. Can I issue my own birth certificate?
Only if you are a legitimate nation. Otherwise you can only issue forgeries.
Q: What determines if my government is legitimate?
Probably the best test of legitimacy is if you can issue birth certificates and they get honored.
Q: What if I was adopted in a closed adoption, or my birth certificate was in a records hall that burned down, or I was born in a culture that doesn't have detailed record-keeping for births?
Then the paperwork may get complicated, but you stll count as being born. Unless you also sprung forth fully adult in arms and armor.
I hope this clears everything up.