Spotting between periods is common and, in most cases, completely normal. Light bleeding outside your regular period can happen for a range of reasons, from ovulation to hormonal birth control to the early stages of pregnancy. That said, persistent or heavy spotting sometimes signals something that needs attention, so understanding the likely causes helps you know what to watch for.
Ovulation Is the Most Common Cause
The most frequent reason for mid-cycle spotting is ovulation itself. Around the midpoint of your cycle (day 14 in a typical 28-day cycle), a sudden shift in hormone levels triggers the release of an egg. That hormonal dip can cause a small amount of bleeding from the uterine lining. Ovulation spotting is usually pink, light red, or brown, lasts just a day or two, and is light enough that you might only notice it when wiping or as a faint mark on your underwear.
If you track your cycle and notice a pattern of light spotting roughly two weeks before your period, ovulation is the most likely explanation. It doesn’t indicate a fertility problem or anything wrong with your reproductive health.
Hormonal Birth Control and Breakthrough Bleeding
Starting or switching hormonal birth control is another very common trigger. Breakthrough bleeding affects roughly 20% of people using low-dose estrogen contraceptives, and it’s especially common during the first pack or cycle. About 75% of users settle into a regular bleeding pattern by the end of their first month, and most have stable cycles by the third month.
This applies to the pill, the patch, and the ring. Hormonal IUDs and implants can also cause irregular spotting, sometimes for several months, as your body adjusts. Missing a pill or taking it at inconsistent times makes breakthrough bleeding more likely. If spotting continues past three months on a new method, it’s worth bringing up with your provider, but in those early weeks it’s expected.
Implantation Bleeding in Early Pregnancy
If pregnancy is a possibility, light spotting one to two weeks after ovulation (often just before your expected period) could be implantation bleeding. This happens when a fertilized egg attaches to the uterine lining. It’s typically light pink or dark brown, lasts one to three days, and is light enough that it won’t fill a pad or tampon. Unlike a period, it doesn’t contain clots.
The timing can be confusing because it falls right around when you’d expect your period to start. The key differences: implantation bleeding stays very light and doesn’t progress into heavier flow the way a period does. A home pregnancy test taken after a missed period is the simplest way to tell the difference.
Perimenopause and Age-Related Changes
For people in their late 30s and 40s, spotting between periods often reflects the hormonal shifts of perimenopause. During this transition, which can begin years before menstruation actually stops, the ovaries produce less estrogen and don’t always release an egg each month. That inconsistency leads to cycles that may be shorter, longer, heavier, lighter, or punctuated by spotting at unexpected times.
These changes are a normal part of aging, but because the risk of conditions like uterine polyps and endometrial changes also increases with age, new or unusual bleeding patterns after 40 are worth discussing with a provider to rule out other causes.
Cervical Sensitivity and Post-Sex Spotting
Some people notice spotting specifically after sex. One common reason is cervical ectropion, a harmless variation where softer cells from inside the cervical canal are visible on the outer surface of the cervix. Somewhere between 17% and 50% of people with a cervix have this variation. Those softer cells are more delicate, so friction during intercourse can cause light bleeding.
Cervical ectropion itself rarely needs treatment. However, post-sex spotting can also be caused by infections or, less commonly, cervical cell changes, so if it happens repeatedly it’s a good idea to get checked.
Infections That Cause Spotting
Sexually transmitted infections, particularly chlamydia, can cause bleeding between periods. Chlamydia often has no symptoms at all, which is part of what makes it tricky. When symptoms do appear, they can include unusual discharge, burning during urination, pain during sex, and spotting between periods or after sex. The bleeding happens because the infection inflames and irritates the cervix.
Gonorrhea can produce similar symptoms. If spotting is accompanied by discharge that looks or smells different from normal, pelvic pain, or a burning sensation, getting tested for STIs is a straightforward next step. These infections are easily treated, but left alone they can lead to more serious complications.
Structural Growths: Polyps and Fibroids
Uterine polyps are small growths that form when cells in the uterine lining overgrow. They’re estrogen-sensitive, meaning they tend to develop and enlarge in response to estrogen. Polyps can cause irregular bleeding, spotting between periods, and unusually heavy menstrual flow. They’re more common as you get older, though they can occur at any age.
Fibroids, which are noncancerous growths in the muscular wall of the uterus, can cause similar bleeding patterns. Both polyps and fibroids are generally benign, but they sometimes need to be removed if they cause persistent symptoms, heavy bleeding, or interfere with fertility.
Thyroid Problems and Hormonal Imbalances
Your thyroid plays a bigger role in your menstrual cycle than most people realize. An underactive thyroid disrupts the chain of hormonal signals that regulate ovulation, which can lead to irregular bleeding, spotting mid-cycle, and changes in flow. Conditions like PCOS (polycystic ovary syndrome) similarly disrupt the hormonal balance needed for regular cycles, leading to unpredictable bleeding patterns.
If spotting comes alongside other symptoms like unexplained fatigue, weight changes, hair thinning, or cycles that have become noticeably irregular, a hormonal issue could be the underlying cause. These conditions are diagnosable with blood work and manageable once identified.
When Spotting Needs Attention
Occasional, light spotting that lasts a day or two is rarely cause for concern, especially if you can connect it to a likely trigger like ovulation, a new birth control method, or the timing of implantation. But certain patterns suggest something worth investigating:
- Spotting that happens most months for six months or more without a clear cause like contraception
- Bleeding heavy enough to soak a pad or tampon outside your regular period
- Spotting accompanied by pelvic pain, unusual discharge, or fever
- Any bleeding after menopause (defined as 12 consecutive months without a period)
- New spotting patterns after age 40, even if they seem minor
Evaluation for persistent spotting typically involves a pelvic exam, sometimes an ultrasound, and possibly blood work to check hormone levels or screen for infection. In most cases the cause turns out to be something straightforward and treatable.