Birth Control

What is Breakthrough Bleeding?

Key Takeaways

So, what is breakthrough bleeding anyway? This guide will help you with everything you need to know about breakthrough bleeding. 

What is breakthrough bleeding?

Breakthrough bleeding is bleeding from the vagina that occurs during pregnancy or between menstrual periods. Sometimes called “spotting,” breakthrough bleeding can be cause for alarm, but there are many non-emergency reasons why you might be seeing blood in your favourite undies.

Breakthrough bleeding usually is fairly light and can range from a faint pink tinge to dark reddish-brown. The colour of the blood indicates how new or old the blood is, similar to the range of menstrual blood colour. Darker blood that ranges to brown is generally older blood, and one of the primary reasons why it shows up later in your menstrual cycle. 

While breakthrough bleeding can range in both colour and volume, if you’re concerned, it's always best to check with your doctor. 

What can cause breakthrough bleeding?

Breakthrough bleeding is fairly common. It often occurs in people who are on the birth control pill or use another form of hormonal birth control, such as an intrauterine device (IUD). While this is one of the most common causes of spotting, there are a number of other causes. As always, if you’re concerned, it’s best to clear things up with your doctor.

1. Breakthrough bleeding in pregnancy

Breakthrough bleeding in pregnancy is more common than you’d think, and it doesn’t always mean there’s something wrong. Up to 25% of pregnant people experience spotting during the first trimester. However, there are some cases where breakthrough bleeding can be cause for concern, so always check with your doctor if you are experiencing breakthrough bleeding during pregnancy.

Breakthrough bleeding in pregnancy can be caused by:

  • Subchorionic hemorrhage or hematoma
  • Sensitive cervix
  • Implantation bleeding
  • Miscarriage or ectopic pregnancy (these are a health emergency and if you suspect a miscarriage or ectopic pregnancy, attend the emergency department or or 911 immediately if concerned)

Always visit a doctor if you are experiencing spotting during pregnancy or suspect you may be pregnant. 

2. Hormonal contraception

The two most popular types of hormonal contraception are the birth control pill and hormonal IUD. Both can cause spotting. 

Birth control pill

Breakthrough bleeding is common in people who have recently started or switched birth control pills. It can occur for a few months until the body regulates to the new contraception. It’s also common in people who use birth control pills to skip their menstrual cycle. This happens when taking pill packs back to back and skipping the placebo pills. 

Generally, breakthrough bleeding on the pill generally occurs when:

  • A pill has been missed or taken at a different time
  • If you are ill, particularly with vomiting, when the pill may not have absorbed properly
  • Have switched birth control pills

If you are starting any new medication, it’s best to consult your doctor to see if there are any drug interactions with your hormonal contraception. If you have been ill with vomiting it’s best to use a back-up method of contraception for a week.


An IUD is a small device that is inserted into the uterus via the vagina and prevents implantation of a fertilized egg. While there are some IUDs that do not contain hormones (such as copper IUDs), many IUDs contain the hormone progestin. Both types of IUDs can cause spotting.

If you are experiencing cramping or pain while using an IUD, this could be indicative of another underlying condition, such as malposition of the IUD, fibroids, endometriosis, or infection, which require medical care. If you are experiencing spotting, pain, and/or cramping, it’s best to check with your doctor.

3. Infection

Infections, such as sexually transmitted infections, can cause spotting. STIs or other bacteria can cause infection in the fallopian tubes, uterus or cervix (cervicitis, endometritis, or pelvic inflammatory disease) or vagina (vaginitis).

Other symptoms of an infection can occur alongside spotting:

  • Heavy periods
  • Unusual odour
  • Pelvic pain
  • Abnormal vaginal discharge
  • Cloudy urine
  • Burning in the pelvis
  • Pain during intercourse
  • Fever

Even if you don’t experience spotting, or your bleeding stops and are still experiencing any of these symptoms, check with your doctor. 

4. Endometriosis

Endometriosis is a common condition that affects up to 10% of the population. For some, it can be quite severe and debilitating and affect many aspects of people’s lives, not just breakthrough bleeding. 

Endometriosis is when the tissue that lines your uterus called the endometrium (the same tissue that is expelled during your menstrual cycle), grows and builds up in other areas of the pelvis, such as outside the uterus, the fallopian tubes or ovaries, and sometimes even on the intestines, bladder, or kidneys. 

During your period, your uterus sheds this lining, but in endometriosis, this other tissue can build up and cause discomfort. Rarely it can cause scarring, bloating, and infertility if not treated. 

Common symptoms of endometriosis include:

  • Unusual bloating
  • Pelvic pain when not menstruating
  • Constipation or diarrhea while menstruating
  • Breakthrough bleeding
  • Nausea during menstruation
  • Severe menstrual pain
  • Pain during sex

5. Fibroids

Fibroids are another common gynecological condition and are growths that form in and around the uterus. Some individuals have no symptoms while some experience extreme discomfort and spotting. Fibroids can also lead to fertility challenges. 

Other symptoms of fibroids can include:

  • Frequent urination
  • Constipation
  • Lower back pain
  • Incomplete voiding
  • Pelvic pressure and pain
  • Heavy periods

The size and shape of fibroids can vary. Some are very small and mostly inconsequential while some can be so large they can distort the uterus. Fibroids can also make vaginal intercourse painful and sometimes contribute to infertility if not treated. 

6. Implantation bleeding

When a fertilized egg implants in the endometrial tissue of the uterus, some of that tissue can break off and be expelled through the vagina, which can show up as spotting. Volume and colour of the blood can vary, ranging from a slight pinkish tinge on the toilet paper or as rust-coloured discharge similar to the end of your period. 

Implantation bleeding is quite common and usually occurs in the middle of your cycle (think about a week after ovulation). Since it takes a fertilized egg roughly a week to travel through the fallopian tube and to the implantation site, spotting generally happens around 6-12 days after conception (or a few days before your first missed period). 

However, if you ever have bleeding and think you might be pregnant, you should always see a doctor to figure out what’s going on.

7. Subchorionic hemorrhage or hematoma

Subchorionic hematoma is when the placenta partially separates from the original implantation site in the uterus. Bleeding volume can vary from light to heavy, and while most subchorionic bleeding is harmless, always consult your doctor if you are experiencing breakthrough bleeding in pregnancy. 

8. Miscarriage or ectopic pregnancy

A miscarriage or ectopic pregnancy both require emergency medical care, so if you suspect you may be having a miscarriage or have an ectopic pregnancy, visit the emergency department or call 911 if you have severe concerns.


A miscarriage is when a pregnancy ends on its own. Up to 20% of pregnancies result in miscarriage, often during the first trimester. 

Not all breakthrough bleeding means miscarriage. If you are experiencing breakthrough bleeding in pregnancy, check with your doctor right away. 

Other symptoms of a miscarriage include:

  • Pain in the abdomen, lower back, or pelvic area
  • Tissue-shedding from the vagina
  • Any vaginal bleeding, regardless of volume, colour, or duration

Ectopic pregnancy

An ectopic pregnancy is an emergency medical situation and can be extremely dangerous, even life-threatening. However, if treated, risk significantly decreases. 

An ectopic pregnancy is when the fertilized egg implants in any area other than the uterus. The vast majority of ectopic pregnancies occur in the fallopian tubes (the tubes that extend from the ovaries to the uterus). As the embryo grows, it puts pressure on the fallopian tube and can lead to rupture. Ectopic pregnancies usually accompany abdominal cramping. If you suspect you may be having an ectopic pregnancy, visit the emergency department or call 911.

9. Cancer

Sometimes breakthrough bleeding can be indicative of cervical or uterine cancer. While it can occur between periods or after sex, it can also show up as irregular or unusual periods. In postmenopausal people, spotting can also indicate cervical cancer. 

To prevent cervical cancer, it’s important to get regular Pap tests. A Pap test is when a swab of cervical cells is taken and analyzed for possible cellular abnormalities. Even if you don’t have breakthrough bleeding or any gynecological concerns, a Pap test can identify precancerous cells in the cervix, allowing you and your doctor to discuss next steps.

How to manage or stop breakthrough bleeding

How to manage or stop breakthrough bleeding depends on the cause. If it requires medical care, you and your doctor can come up with a treatment solution. In some situations, like in a change in birth control pill, spotting will resolve on its own. 

Your doctor can help you with management tips more catered to your particular needs.

When to see your doctor about breakthrough bleeding

While breakthrough bleeding isn’t always a concern, it’s never too early or late to see a doctor about it, particularly if you’re experiencing other symptoms. Underlying causes like STIs, inflammation, or complications with pregnancy require medical assistance. For individuals who have reached menopause (if you haven’t had a period in 12 months), check with your doctor if you notice bleeding. If you think you might be pregnant and have spotting, you'll also want to see a doctor urgently.

Medically reviewed by


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