2 mc in a row, am i doomed?

kasey
has anyone had 2 consecutive early miscarriages and then had a successful pregnancy? i had a mc in march and then i had one in may. both around 4-5 weeks.  i *might* be pregnant again but i am not sure. i am scared and just need to know that i am not doomed to lose every one. i have a 4 year old and dont understand why this is happening this time around.
- the only difference seems to be that i started taking penatals before i got pregnant with my daughter- and i did not start taking a vitamin until after this last mc. i wonder if that will make a difference (nueral tube defects??) i had no idea that they develop in the first 4 weeks.
anyway, any succes stories after 2 miscarriages in a row would be such an encouragement right now
(and those of you that pray, i could really use some right now)