Bleeding that turns up when you are not expecting it is unsettling in a way that a heavy period is not. A brown smudge a week after your period finished, a pink streak in the middle of the month, a few days of light bleeding that stops before you work out what it was.
The short version is that it is usually not serious and it always needs checking. Those two things are both true at once, and most of the worry around this comes from treating them as if only one can be. This guide goes through what counts, what usually causes it, what is urgent, and what to bring to the appointment.
What counts as bleeding between periods
Any bleeding or spotting outside your period counts, however light. The American College of Obstetricians and Gynecologists groups it under abnormal uterine bleeding, alongside bleeding after sex, periods that soak through a pad or tampon every hour, bleeding that lasts more than 7 days, cycles longer than 35 days or shorter than 21, cycle lengths that vary by more than 7 to 9 days, no period for 3 to 6 months, and any bleeding after menopause.
That word abnormal is doing less work than it sounds like. It is a category that says look into this, not a diagnosis and not a warning. Plenty of what lands in it turns out to be a contraceptive settling in or a harmless growth.
It is worth separating spotting from a period in your own head, because the two get logged as the same thing and they are not. Spotting is light, often brown or pink, and does not need a pad. Day 1 of a cycle is the first day of real flow. If you record a spot as a period start, every cycle length and every prediction that follows it is wrong, and the record you take to a doctor is wrong too.
The common causes
The NHS puts three causes at the top for bleeding between periods.
- Hormonal contraception. Breakthrough bleeding is a known effect of the pill, the implant, the injection and hormonal coils, and it is most common in the first few months of a new method. ACOG lists the copper coil separately as a cause of heavier periods, especially in the first year.
- Polyps and fibroids. Small growths in or around the womb or on the cervix. Both are non-cancerous and both can cause irregular bleeding.
- Sexually transmitted infections. Chlamydia is the one named. This is a large part of why the NHS routes people to a sexual health clinic as readily as to a GP, and why a swab is a standard part of the appointment.
ACOG adds several more.
- Problems with ovulation. Cycles where ovulation does not happen can bleed irregularly. This covers the first years after periods start, perimenopause, and conditions including PCOS and an underactive thyroid.
- Adenomyosis. The lining of the womb grows into the muscle wall. Heavy bleeding and period pain that gets worse with age are the signs.
- Bleeding disorders. Worth raising if your periods have been heavy since they first started, or if you bruise easily, bleed after dental work or get frequent nosebleeds.
- Medications. Blood thinners and aspirin can make menstrual bleeding heavier.
- Cancer of the womb lining. Uncommon, and most cases are diagnosed in women past menopause in their mid-60s. It is on this list because abnormal bleeding is an early sign and early treatment works well, which is the whole argument for getting checked rather than waiting.
Pregnancy is its own branch. Implantation bleeding can happen at the start of a pregnancy, and a pregnancy test is usually the first thing done at the appointment.
When it is urgent
Two situations do not wait for a routine appointment.
- A missed period, unusual bleeding and abdominal pain together. The NHS says to ask for an urgent GP appointment or get help from NHS 111, because this can be a sign of an ectopic pregnancy.
- Soaking through a pad or tampon every hour for more than two hours, with chest pain, shortness of breath, or feeling lightheaded or dizzy. ACOG says to seek emergency care straight away.
Any bleeding after menopause needs checking on its own, without waiting to see whether it happens again.
What happens at the appointment
The NHS describes a fairly short list. You are asked about your symptoms and history, and you may have a pregnancy test, a blood test, a test for sexually transmitted infections by urine sample or swab, and an examination of the vagina and cervix. If more is needed, that means an ultrasound scan, a colposcopy, or a hysteroscopy, which is a thin lighted scope that lets a doctor see inside the womb.
Treatment depends entirely on the cause, so there is not much point reading ahead on that. Hormonal methods are often the first thing tried when the cause is ovulation-related, which is worth knowing if you are not looking for contraception, because it is a conversation to have rather than a decision to receive.
What to bring
This is the part you can do before you go, and it is the part that changes the appointment most. ACOG asks you to keep track for several weeks beforehand and to note the dates, the length, and the type of bleeding, meaning light, medium, heavy or spotting. It says a cycle-tracking app is a fine way to keep that record.
Worth having with you:
- Every bleeding day, with spotting marked as spotting.
- The first day of each real period, so your cycle length and how much it varies can be read off the record.
- Which contraception you use and the date you started or changed it.
- Pain, and where it was.
- Bleeding after sex, which is asked about separately.
Three months of dates answers questions that memory cannot. Keeping a period diary turns a vague account into something a clinician can act on in the ten minutes you have.
How Plum fits in
We build Plum, so here is the honest version of what it does with this. Plum will not tell you what your bleeding means. Nothing in an app can, and the causes above are separated by a swab and a scan, not by a pattern.
What it does is keep the record ACOG is asking for. Logging a day takes a tap, spotting is recorded as spotting rather than as a period, and you choose which categories to track, so you can keep it to bleeding alone or add pain, mood and the rest. Plum works out your usual cycle length from what you log and predicts the next period, and if your cycles are irregular it will say so rather than pretend to a date.
Plum shows no ads and never sells personal data. It does require an account and syncs your data to our servers, encrypted in transit and at rest, and you can delete your account and data in the app at any time. If you share a cycle with a group, the group sees a summary of your cycle dates and never your symptoms or notes.
