Spotting Between Periods: The Honest List of What Causes It

Bleeding between periods can have a lot of different causes and is not usually serious, but the NHS says it should always be checked by a GP or a sexual health clinic. Both halves of that sentence are the NHS's, and printing only the first one would be the dishonest move. There is one combination that does not wait: if you have recently missed a period, have unusual vaginal bleeding and have pain anywhere in your tummy, the NHS says to ask for an urgent GP appointment or help from NHS 111, because it could be a sign of an ectopic pregnancy. Nothing about the colour, the timing or the amount tells you the cause, and no source this site can cite says otherwise.

"Spotting" is the word most people type, so it is the word used here. It is worth knowing that the NHS page this article leans on does not use it at all — it calls the same thing vaginal bleeding between periods or after sex — while ACOG does use it, listing bleeding or spotting between periods among the things it counts as abnormal uterine bleeding.

The one thing on this page that cannot wait

ACOG publishes a second emergency line that belongs alongside it, about volume rather than timing: if you are changing pads or tampons every hour for more than 2 hours in a row and also have chest pain, shortness of breath or lightheadedness, seek emergency medical care right away.

The honest list of causes

These are the NHS's, and they are worth reading as a list rather than as a set of possibilities to try on. Common causes of bleeding between periods or after sex include:

• hormonal contraception, such as the contraceptive pill;
• small growths in and around the womb, such as polyps or fibroids;
• sexually transmitted infections.

And the sentence that usually gets left out: the NHS also says it can sometimes be a sign of cancer. That sits in the same paragraph as "not usually serious", and both are true. Printing only the reassuring half would leave somebody deciding not to bother; printing only the frightening half would be its own kind of lie. The reason the NHS says always get it checked is precisely that the list contains ordinary things and serious ones and the bleeding itself does not distinguish between them.

Bleeding after sex is on the same NHS page and gets the same answer: checked by a GP or a sexual health clinic, whatever else you think is going on. A sexual health clinic is often the faster route and it can test for the infection half of the list in the same visit.

What it looks like tells you nothing

This is the part of the subject where the internet is at its most confident and has the least behind it. Brown means old blood, pink means this, a single day means that — nothing this site is allowed to cite supports reading a cause from the colour, the volume or the day of the month it landed on. So this page does not, and any page that does is guessing on your behalf.

What is worth recording is not what it looked like but when it happened and what else was going on: the date, how many days, whether it followed sex, and whether anything else changed that month. That turns a vague "I've been spotting" into something a five-minute appointment can work with. The printable symptom tracker has room for it day by day, and the printable period tracker keeps the start dates next to it so the pattern of what is bleeding and what is a period stays visible.

Early pregnancy, stated at its real strength

This is the other reason people search for this at two in the morning, and it deserves the actual evidence rather than a story.

The NHS says that if you have a regular monthly cycle, the earliest and most reliable sign of pregnancy is a missed period, and that in the first few weeks you may also have a bleed similar to a very light period, with some spotting or only losing a little blood, which is called implantation bleeding. That is the whole of what it says, and it is a description of something that happens, not a test you can apply to what you are looking at.

The research goes further in one direction only — how common bleeding is, not what it means. Observational studies have shown first-trimester bleeding in 7 to 24% of pregnancies, and in a cohort of 3,978 women, 986 of them — 26% — reported it. The same paper says the causes of first-trimester bleeding are less well understood and that results in general have been inconsistent.

So: early bleeding is common, it is named by the NHS, and nobody can tell you from a description whether that is what yours is. "Spotting means implantation" is not a conclusion any of that supports. If pregnancy is possible, a test is the thing that answers the question rather than the appearance of the blood — the pregnancy test calculator works out from your own dates when a test would mean something, and is straight about why a negative taken early can be wrong. If the period simply has not arrived, why a period is late covers the ordinary explanations and the point at which the NHS says to see a GP.

Where this sits among the other bleeding questions

Three different questions get muddled together, and separating them is most of the work.

Bleeding when a period is not due is this page. The answer is that it is usually not serious and should always be checked.

Too much bleeding during a period is a different question with concrete tests behind it — changing a pad or tampon every 1 to 2 hours, clots larger than about 2.5cm, periods lasting more than 7 days. Those are set out in what actually counts as a heavy period. The NHS also names bleeding between periods, and bleeding after sex, among its reasons to see a GP about heavy periods, so the two questions do meet.

Periods arriving at unpredictable intervals is the third, and the NICHD counts bleeding between periods among its menstrual irregularities, alongside cycles more than 35 days apart, cycles less than 21 days apart, bleeding that exceeds 8 days and cycle-to-cycle variation of more than 20 days. It says 14% to 25% of women have irregular cycles of some kind. That question is answered in irregular periods.

What to do this week

Write down today's date and what happened, before it blurs into last month. Book the appointment — the NHS's word is "always", and this is a five-minute conversation rather than a big one. Take the dates with you rather than a memory of them.

And treat the two urgent rules at the top of this page as the exceptions they are. Everything else here is a reason to make an appointment, not a reason to panic at 2am, and the difference between those two is the only thing this page is really for.