Bright red bleeding appearing about one week before an expected menstrual period is categorized as intermenstrual bleeding or “spotting.” This color indicates fresh blood, unlike the darker brown of older blood. Bleeding seven days before the expected period suggests a disruption in normal hormonal or physical processes. While often common and benign, this unscheduled bleeding can sometimes signal conditions requiring medical evaluation.
Implantation and Early Pregnancy Bleeding
One frequent reason for bright red spotting a week before a period is embryo implantation. This occurs when a fertilized egg attaches to the blood-rich lining of the uterus, typically six to twelve days after ovulation. This timing often places the bleeding seven to ten days before the expected start of menstruation.
The attachment process can disrupt small blood vessels in the uterine lining, causing a small amount of light, fresh bleeding. Implantation bleeding is usually very light, lasting a few hours up to two days, distinguishing it from a regular period. Although typically pinkish or brown, the blood can appear bright red if it is very fresh.
Any bleeding in the luteal phase, especially if pregnancy is possible, requires consideration of potential complications. Rarely, bleeding at this time could signal an ectopic pregnancy or a threatened miscarriage. A positive home pregnancy test followed by bright red bleeding or severe cramping requires immediate consultation with a healthcare provider.
Hormonal Fluctuations
Bleeding in the week before a period often stems from subtle shifts in reproductive hormones. The second half of the cycle, the luteal phase, is dominated by progesterone, produced after ovulation. Progesterone’s function is to stabilize and maintain the uterine lining.
Spotting can occur if progesterone levels are insufficient or drop prematurely, sometimes associated with a luteal phase defect. When hormonal support falters, the uterine lining may start to shed in small amounts before the scheduled period. A short luteal phase, defined as less than 11 days, is often observed in individuals with this pre-period spotting.
Systemic endocrine conditions that affect hormone regulation can also destabilize the uterine lining. For instance, thyroid dysfunction, such as hypothyroidism, can alter the balance of reproductive hormones, causing erratic bleeding. Similarly, perimenopause can cause unpredictable spotting as ovarian function becomes irregular and hormone production fluctuates widely.
Structural and Physical Causes
Unscheduled bleeding can originate from physical anomalies or irritation within the reproductive tract, not just hormonal signals. Benign growths like uterine fibroids and polyps are common structural causes of intermenstrual bleeding. Polyps are soft projections from the uterine or cervical lining, while fibroids are dense, non-cancerous tumors of the uterine muscle wall.
These growths contain blood vessels and can become easily irritated, leading to bright red spotting, especially after physical activity or intercourse. Polyps are often highly vascular and fragile, causing them to bleed upon contact. Cervical ectropion, where delicate glandular tissue is present on the outer cervix, can also cause bright red bleeding due to the tissue’s sensitivity to friction.
Inflammation or infection of the cervix or vagina can make tissues fragile and prone to bleeding. Sexually transmitted infections (STIs), such as chlamydia or gonorrhea, can cause cervicitis (cervical inflammation). This inflammation increases tissue sensitivity, meaning minor irritation can result in bright red bleeding a week before the period.
Medications and Contraception
Hormonal medications are a frequent source of unscheduled bleeding before a period. Hormonal contraceptives, including the pill, patch, ring, implant, or injection, can cause “breakthrough bleeding.” This is common when starting a new method or using a low-dose estrogen formulation.
The synthetic hormones can cause the uterine lining to become thin and fragile, a process called endometrial atrophy. When the lining lacks sufficient hormonal support, it sheds irregularly between expected withdrawal bleeds. Inconsistent use, such as missing a pill, also causes a temporary drop in hormone levels that can trigger unscheduled bleeding.
Intrauterine devices (IUDs), both copper and hormonal, can also lead to pre-period spotting. The non-hormonal copper IUD can cause increased uterine inflammation, resulting in heavier bleeding and spotting, especially in the first few months. Hormonal IUDs cause endometrial thinning, which also leads to unpredictable spotting, though this often improves over time.
Next Steps
Unscheduled bright red bleeding has diverse causes, many of which are temporary hormonal adjustments. However, seeking professional medical advice is prudent to rule out underlying conditions. Tracking the pattern of the bleeding—including color, duration, and volume—provides valuable information for a healthcare provider.
Immediate medical attention is necessary if the bleeding is heavy, equivalent to a full period, or is accompanied by severe abdominal or pelvic pain, dizziness, or fever. If pregnancy is suspected, take a home pregnancy test and contact a doctor for guidance. Consulting a gynecologist is the most effective step to determine the specific cause and ensure appropriate management, especially if spotting is persistent.