Sincy, what do you think this is about? I do suspect that it is normal to worry about all sorts of things at this stage...you are so close, have come so far, and yet everything you have dreamed about is still a dream and unknown, so it is bound to be scary. I remember people in my ante-natal classes voicing all sorts of 'nightmares', fear of holding their baby in case they somehow catapulted it out of a window was one that I remember coming up!
When your baby is born, not only will it be wonderful and lovable WHATEVER, but in a funny kind of way, it will seem 'ordinary', in the sense that it will finally be real life, not a dream or longed for fantasy, but along with the fantasy element will disappear the fears, too. (don't worry, loads more will erupt...sleep, health, 'that' cry, what does it mean?...).
Do you have a specific real fear of any kind of birthmark? Of course, there are Mums who meet their new baby and discover that there IS some difference - I am one of those - and, although statistically it is unlikely, if you did happen to find yourself in that position, you would STILL find that you love your baby fiercely and with pride and pleasure.