If the bleeding has only happened after sex, it is less of a worry.
"There can be nothing as unnerving as finding out that you have spotting or bleeding after sex – while you’re pregnant.
Firstly, don’t panic. The baby is well protected in your uterus (which is sitting safely above your vagina), and sex is not going to hurt your baby. A mucus plug seals the cervix and your baby is surrounded by warm, amniotic fluid, in the amniotic sac. So don’t be mistaken thinking that you’ve hurt your baby.
Can Sex During Pregnancy Cause A Miscarriage?
It is very unlikely that sex will result in you miscarrying while pregnant. If you have a history of miscarriage, I am sure your doctor has advised you to hold off with intercourse for the first trimester.
The reason spotting or light blood loss can occur after sex is due to increased blood supply. Little blood vessels around the softened cervix rupture, which are in more plentiful supply during pregnancy.
If you’ve had vigourous or rougher sex than usual, maybe drop things down a notch and see how that goes next time. But of course, this isn’t a guaranteed way to prevent any spotting.
Any blood loss should be mentioned to your doctor or midwife, just to be on the safe side. It’s absolutely worth your own peace of mind too."
From here