Hello,
Welcome to the ehealthforum and I am really glad to help you out. Your concern is regarding the spotting that you are having in the first trimester. Slight spotting is common during the first trimester of pregnancy. During pregnancy the cervix becomes more sensitive and engorged with blood. Any trauma even slight like in intercourse can give rise to such a bleeding.
The other possibility is of threatened miscarriage. To prevent threatened miscarriage, I would suggest you to avoid intercourse especially during the first trimester. If the bleeding becomes severe or is associated with any cramps, then the chances of miscarriage are there. Immediate medical intervention is then required.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.