I ate a half a sesame seed bun and 9 weeks pregnant. i read it can cause a miscarriage. should i worry?

No: There is no correlation between sesame seed buns and miscarriage. Even if you read on the internet and I can't imagine where that there is a correspondence to sesame seeds and miscarrige then China would be in trouble as they use sesame seed oil in their cooking all the time. Last I heard this was the most populous country in the world, Do not fear!