Hey thanks for your faith in the health care Magic Bleeding in the first trimester is not always a problem. It may be caused by: Having sex An infection The fertilized egg implanting in the uterus Hormone changes Other factors that will not harm the woman or baby More serious causes of first-trimester bleeding include: A miscarriage, which is the loss of the pregnancy before the embryo or fetus can live on its own outside the uterus. Almost all women who miscarry will have bleeding before a miscarriage. An ectopic pregnancy, which may cause bleeding and cramping. A molar pregnancy, in which the pregnancy does not form properly..thank you