it might affect her fertility rate in the future, well, not a
high chance but there is always risk so best is, don't get pregnant
in the first place. 
any case, there isn't any true right or wrong in getting an
abortion, she must be aware of that, usually, its the mental health
that suffers the most for people like her.
after reading more posts, i feel the need to stress the above
point. whether she is your friend, or you, or your girlfriend, or
whoever, this point must be made clear or it will leave an
emotional scar in her for the rest of her life and her
relationship. tell her, its alright, if she believes it is the
right thing to do, than go do it.
its a question of.. "does the
caged bird desires to fly in the open skies?" we are not
her, we can never feel what she is in, but the reverse may be true,
she may be confused by other people's opinions and suffers as a
result.
blaming her will never solve the issue at hand. while we may be
concerned for the possibility of new life, shouldn't we be concern
about the health of the her at the current situation instead of
asking what ifs and what should have been scenerios.