Subject: Why was I born with a 'y-shaped umbilical cord?'

I am a 30 year-old female who was born with what was described as a "y-shaped 
umbilical cord." I believe there was only one placenta with no evidence of a 
twin. I also think that the cord was attached to me in once but attached to 
the placenta in two different areas.  The doctor was very excited with my 
umbilical cord telling my mother that my umbilical cord was very rare.  I'm 
just curious as to why this happened and how rare it really is.  It is very 
difficult to find any information on this because I dont even know what it is 
called, so any information would be greatly appreciated. 
Thank You.

Re: Why was I born with a 'y-shaped umbilical cord?'