Spotting Between Periods: What Causes It?

Most spotting between periods has a simple explanation: ovulation, a hormonal contraceptive that has not settled yet, a missed or late pill, or a small amount of old blood clearing after a period. A single light episode in an otherwise regular cycle is rarely a sign of anything serious.

The pattern that changes the answer is persistence. Spotting that recurs for more than about three cycles, bleeding after sex, or any bleeding at all after the menopause should be examined rather than watched, not because these usually mean cancer, but because they are the symptoms through which cervical and womb cancers are most reliably found early.

The common causes#

Hormonal contraception. Breakthrough bleeding in the first three months of a new pill, implant, injection or hormonal coil is expected. So is spotting after a missed pill, or after vomiting or diarrhea that reduced absorption.

Ovulation. A brief estrogen dip mid-cycle produces light spotting in some women, often with a twinge on one side.

Infection. Chlamydia, gonorrhoea and cervical inflammation frequently present exactly this way, sometimes with no discharge or pain at all.

Structural causes. Cervical or endometrial polyps, fibroids and adenomyosis. Polyps in particular are a classic cause of unpredictable spotting and are usually easy to remove.

Cervical ectropion. Common in younger women, in pregnancy and on the pill. Delicate cells sit on the outer cervix and bleed easily, especially after sex. Benign, and treatable if bothersome.

Perimenopause. In the years before periods stop, cycles become erratic and spotting is frequent. It is still worth mentioning, because this is also the age at which endometrial problems become more common.

Pregnancy. Implantation bleeding, early miscarriage and ectopic pregnancy all cause bleeding. A pregnancy test is part of the assessment for anyone who could be pregnant.

What assessment looks like#

A doctor will ask about the timing, the amount, whether it follows sex, your contraception, your last cervical screening and whether you could be pregnant. Expect an examination that includes looking at the cervix, swabs for infection, a pregnancy test where relevant, and often a pelvic ultrasound. From around age 45, or where the picture suggests it, sampling of the womb lining is arranged.

What not to do#

Do not stop a contraceptive method on your own because of spotting. You risk an unplanned pregnancy and lose the information about whether the method was the cause. Do not skip cervical screening because you are already being investigated; they answer different questions. And do not let a normal screening result reassure you out of getting persistent bleeding checked, since screening tests for cervical changes only, not for the womb lining.

Where this fits#

Spotting rarely travels alone. Cycle length, pain, flow and the pattern of change over time all belong to the same picture, and reading them together is what makes a consultation useful. The fuller guide to painful and irregular periods is written for that.