I had anti C, with my thrid child and experianced pretty much what Poledra has just outlined.
The anti C was discovered straight away, but the levels were of no significance. However, they continued to rise, and when they got to a certain level I had to have my car trasnferred to a larger hospital with a resus unit.
I was scanned fortnightly to check for hydrops (fluid under the skin). Hydrops indicates anemia and or jaundice (can never remember which). All of my scans were always fine.
I also had blood taken very regularly.
In the end I had Ds by c-section at 37 weeks (c-section and 37 not related to the anti C).
After he was born he quickly became quite jaundiced and had phototherapy on a billibed. After a week his levels were low enough for us to go home and thankfully they continued to go down. Unfortunatly he then became anemiac for a while. He narrowly escaped a blood transfusion.
I was told not to get pregnant again, as my levels would start off where they left and could rise agaihn. However when I asked about how high levels effect subsequent babies, I was tols that they cannot tell how a baby will be effected until it happens. The levels could be sky high and baby be fine, or the levels could be low and the baby be poorly, they just cannot tell.
At the end of the day, you will be closley monitered and so shouldn't have any problems at all, and if you do encounter any, they are treatable, so do not let them scare you, it will be fine.