Intermenstrual Bleeding (Bleeding Between Periods)

What counts as intermenstrual bleeding

A typical menstrual cycle lasts 24 to 38 days, with bleeding for up to 8 days. Intermenstrual bleeding (IMB) is bleeding at any other time. It can be light brown or pink spotting that only shows when you wipe, or red bleeding that needs a pad. Doctors also ask about postcoital bleeding (bleeding after sex), because it shares many causes with IMB and points toward the cervix.

IMB is one part of the wider picture of abnormal uterine bleeding, which also includes heavy, prolonged, or unpredictable periods. If your periods themselves are irregular, see unpredictable menstruation.

Common causes of bleeding between periods

Hormonal contraception

Breakthrough bleeding is the most common reason for spotting between periods in people using hormonal birth control. It is especially common:

• in the first 3 months of a new pill, patch, ring or injection
• with progestogen-only methods (mini-pill, implant, injection, hormonal IUD)
• with missed, late or vomited pills, or when certain medicines (such as some anti-seizure drugs and rifampin) or the herbal remedy St John's wort lower hormone levels
• with continuous or extended pill use to skip periods

Smoking increases breakthrough bleeding on the pill. If it persists beyond 3 months, a doctor will check for infection and pregnancy before changing your method.

IUDs

Copper IUDs often cause heavier periods and spotting in the first few months. Hormonal IUDs cause irregular spotting early on, then often lighter or absent periods. See IUD-related bleeding for when bleeding with an IUD needs checking.

Ovulation

About 1 in 10 people notice light spotting mid-cycle, around ovulation, from a brief dip in estrogen. It lasts 1 to 2 days, may come with one-sided twinges (mittelschmerz), and is harmless.

Pregnancy

Light bleeding is common in early pregnancy and can happen around the time a period would be due (implantation bleeding). Bleeding can also signal miscarriage or an ectopic pregnancy, which is a medical emergency. If there is any chance you are pregnant, take a test.

Infection

• Chlamydia and gonorrhea: these infect the cervix (cervicitis), making it fragile and prone to bleeding, especially after sex. Chlamydia often causes no other symptoms.
• Pelvic inflammatory disease: infection spreading to the womb and tubes, with pelvic pain, fever and discharge.
• Vaginitis: trichomoniasis or atrophic vaginitis can cause spotting.

Growths in the cervix or womb

• Cervical polyps: small, soft, finger-like growths that bleed easily, often after sex. Removing them is quick.
• Endometrial polyps: growths in the womb lining, a common cause of IMB, especially from the late 30s on.
• Uterine fibroids: fibroids that bulge into the womb cavity (submucosal) can cause bleeding between periods as well as heavy periods.
• Adenomyosis: womb lining growing into the muscle wall, causing heavy painful periods and sometimes spotting.

Hormonal changes

• Perimenopause: in your 40s, cycles become irregular and bleeding may come at unexpected times.
• Polycystic ovary syndrome (PCOS) and other causes of irregular ovulation.
• Thyroid problems, especially an underactive thyroid.
• Stopping or starting hormone therapy.

Cancer and precancer

Cervical cancer can first show as bleeding after sex or between periods. Endometrial (womb) cancer is more common after menopause but can cause IMB in younger people with risk factors such as obesity, PCOS or long stretches without periods. These causes are much less common, but they are the reason persistent IMB needs examining.

Other causes

• Injury to the vagina, for example from sex or a forgotten tampon
• Blood thinners and bleeding disorders
• Retained tissue after childbirth, miscarriage or abortion

Causes by age

How doctors find the cause

Expect questions about the timing and amount of bleeding, your periods, contraception, sexual history, cervical screening history, pain, discharge and medicines. Keeping a 2 to 3 month bleeding diary helps.

Tests may include:

• Pregnancy test
• Speculum and pelvic exam to look at the cervix for polyps, inflammation or abnormal areas
• Swabs for chlamydia, gonorrhea and other infections
• Cervical screening (Pap and HPV test) if due, or a colposcopy if the cervix looks abnormal
• Blood tests: blood count for anemia, thyroid function, sometimes hormone levels
• Transvaginal ultrasound to look for polyps, fibroids or a thickened womb lining
• Endometrial biopsy or hysteroscopy for persistent bleeding, especially over age 45 or with risk factors

Treatment

Treatment depends on the cause:

• Breakthrough bleeding: often settles with time. If not, switching to a pill with a different dose or type of hormone usually helps.
• Infections: antibiotics, with partner treatment for STIs.
• Polyps: removed during a simple outpatient procedure.
• Fibroids and adenomyosis: hormonal treatments, a hormonal IUD, or procedures to remove fibroids.
• Hormonal imbalance: treating thyroid problems, or cycle control with hormones for PCOS or perimenopause.
• Precancer and cancer: treatment by a gynecologist or gynecologic oncologist.

Frequently asked questions

Is bleeding between periods normal?

Occasional light spotting can be normal, especially around ovulation or in the first months of hormonal birth control. Bleeding that happens regularly, follows sex, or occurs after menopause is not normal and should be checked.

What are the common causes of intermenstrual bleeding?

The most common causes are hormonal contraception, IUDs, ovulation, early pregnancy, chlamydia and other infections, and cervical or endometrial polyps. Fibroids, perimenopause and thyroid problems are also common. Cancer is a less common but important cause.

Can stress cause spotting between periods?

Severe stress can disrupt ovulation and lead to irregular cycles and unexpected bleeding. But stress should not be assumed to be the cause of repeated spotting until a doctor has ruled out pregnancy, infection and polyps.

Is spotting between periods a sign of pregnancy?

It can be. Light spotting around the time your period is due may be implantation bleeding. Bleeding in pregnancy can also mean miscarriage or ectopic pregnancy. Take a pregnancy test, and get urgent help if you have pain or feel faint.

When should I worry about intermenstrual bleeding?

See a doctor if it happens over several cycles, follows sex, is heavy, comes with pain, fever or unusual discharge, or occurs after menopause. Get emergency care for heavy bleeding with dizziness or severe one-sided pain if you might be pregnant.