Spotting one week prior to the onset of a menstrual period can be linked to dozens of causes dependent on a woman's former cycles, sexual activity, birth control method and age. According to WebMD, birth control pills and intrauterine devices are largely responsible.
WebMD explains that birth control pills that are not taken at the same time daily may cause bleeding prior to a woman's period. During the first few months of starting a birth control pill, spotting before a period is common in most women. Other causes of spotting before a period are polycystic ovarian syndrome, sexually transmitted infections, pelvic organ infections (more prevalent after intercourse or douching), pelvic inflammatory disease, extreme stress and pregnancy.
Implantation bleeding may be the cause of the spotting. Implantation bleeding generally occurs mid-cycle. According to Huggies Australia, 25 to 30 percent of women experience implantation bleeding in the earlier weeks of pregnancy. Other reasons spotting may occur around one week before a period are general hormonal imbalances, medication side effects, reproductive organ cancer, ectopic pregnancy or blood-thinning medications. A pap smear may also cause this bleeding.
WebMD explains that age may be a factor in spotting. Women over the age of 40 may be entering perimenopause if they experience spotting between periods.