The blood is usually either light red or dark reddish brown, much like the blood at the beginning or end of a period. However, depending on the cause, it may resemble regular menstrual blood.
Breakthrough bleeding frequently occurs in women who use the pill or another form of contraception, such as an intrauterine device (IUD). However, many medical conditions can also cause irregular vaginal bleeding. Anyone unsure of the cause should consult a doctor.
In this article, we examine some of the most common causes of breakthrough bleeding, as well as management strategies and when to seek professional advice.
The following factors can cause breakthrough bleeding in women who are not pregnant:
- hormonal contraception
Breakthrough bleeding may be caused by a variety of medical conditions.
Women who use hormonal birth control often experience breakthrough bleeding, particularly if they have recently switched contraceptive methods. Breakthrough bleeding may occur for several months, as the body adjusts to the new form of birth control.
Breakthrough bleeding is also common in women who misuse birth control pills to skip their periods.
Monthly packs usually contain 3 weeks of hormonal pills and an additional week of placebo pills. During this final week, a period will occur because the person is not receiving contraceptive hormones.
Some women wish to skip their periods. They may take 3 weeks of hormonal pills, then begin another 3 weeks of hormonal pills right away. Most doctors believe that this is safe for up to 3 months at a time.
Other hormonal contraceptive pills, some containing ethinylestradiol and levonorgestrel, extend the amount of time between periods. For example, a person taking this medication may get a period every 3 months. This method of contraception is also likely to cause breakthrough bleeding.
Women taking hormonal contraceptives may be more likely to experience breakthrough bleeding if they:
- miss a pill or take one at a different time
- are ill, especially if they are vomiting or having diarrhea
- starting any new medication
IUDs are popular forms of birth control. No daily pill is required, and a device can be functional for several years.
Hormonal IUDs release a contraceptive medication called progestin, while copper IUDs prevent pregnancy without the use of hormones. Both types cause changes to the menstrual cycle, and any such disruption may lead to breakthrough bleeding.
This bleeding is especially common in the first 3 months after the IUD is inserted.
The following infections and conditions can cause breakthrough bleeding:
- sexually transmitted infections (STIs), such as chlamydia or gonorrhea
- pelvic inflammatory disease
An infection may cause additional symptoms. These can include:
- cloudy urine
- pelvic pain
- unusual odor
- abnormal vaginal discharge
- burning in the pelvis
- pain during intercourse
- heavy periods
The issues above all require medical intervention.
Endometriosis occurs when tissue similar to the lining of the uterus grows elsewhere in the pelvic area. This tissue may develop in the ovaries or fallopian tubes, or around the bladder or bowels.
Endometriosis causes a range of symptoms, including:
- severe pain during menstruation
- pelvic pain when not menstruating
- pain during sex
- nausea during a period
- constipation or diarrhea during a period
- bleeding or spotting between periods
This pain may be so severe that a person cannot engage in regular activities.
Endometriosis may also make becoming pregnant difficult.
Uterine fibroids are abnormal growths that form in or around the uterus. There are many causes, including genetics and hormones.
Some people with uterine fibroids have no symptoms. Others experience breakthrough bleeding. Additional symptoms include:
- pelvic pressure and pain
- heavy periods
- frequent urination
- a backache
- leg pain
- incomplete voiding
Fibroids may be very small or large enough to distort the uterus.
Breakthrough bleeding in pregnancy
As many as 30 percent of people who have been pregnant experienced breakthrough bleeding in the early stages.
This can indicate:
- a sensitive cervix
- implantation bleeding
- subchorionic hematoma
- a miscarriage or ectopic pregnancy
Any time vaginal bleeding occurs during pregnancy, consult a doctor.
The cervix is located at the base of the uterus. During pregnancy, it softens and becomes more sensitive. Intercourse and vaginal exams may be more likely to cause irritation.
If bleeding from the cervix is not related to intercourse or an exam, it may be a sign of cervical insufficiency. This occurs when the cervix begins to open before the baby is fully developed, increasing the risk of premature delivery.
This occurs when the fertilized egg first becomes implanted in the uterus.
Implantation bleeding typically occurs 6–12 days after conception and a few days before the first missed period.
This bleeding will often be so light that no tampon or pad is needed. Many people with implantation bleeding are not yet aware that they are pregnant.
This occurs when the placenta separates from the original site of implantation. The bleeding that results may be light or heavy.
Subchorionic hematomas are often harmless, but a doctor should evaluate any bleeding during pregnancy.
Miscarriage and ectopic pregnancy
It is important to speak to a doctor if vaginal bleeding occurs during pregnancy.
Even heavy bleeding does not always result in a miscarriage. According to the American Pregnancy Association, about 50 percent of women who experience bleeding in the first trimester of pregnancy do not miscarry.
A miscarriage happens when a pregnancy ends on its own within the first 20 weeks. After 20 weeks, this is called a stillbirth. As many as 25 percent of pregnancies result in miscarriage.
Ectopic pregnancies are much less common and occur when an embryo implants in a fallopian tube instead of the uterus.
Bleeding caused by a miscarriage or ectopic pregnancy may be heavy and accompanied by abdominal cramping.
Ectopic pregnancies can be very dangerous if not treated promptly. If a person suspects that they have an ectopic pregnancy, they should seek immediate medical care.
When to see a doctor
Breakthrough bleeding may not be a cause for concern. It is often a side effect of contraception or cervical irritation. Minor causes of breakthrough bleeding usually resolve without medical intervention.
However, consult a doctor if other symptoms accompany breakthrough bleeding. Issues such as STIs or fibroids can cause complications if left untreated.
If unexplained vaginal bleeding occurs during pregnancy, see a doctor. In some cases, bleeding may simply indicate a sensitive cervix, though it may indicate a more severe issue.
An alternative form of contraception may be suggested if the current method is causing bleeding.
Treatment for breakthrough bleeding usually depends on the cause. Mini pads or tampons may provide all the management needed.
In cases of infection, a doctor will prescribe antibiotics or other medications. If a person's contraception is causing the bleeding, a doctor may recommend a different brand or a different method.
A doctor will recommend medication and occasionally surgery to treat conditions such as fibroids and endometriosis.
Cervical irritation often requires no treatment. If a person has a subchorionic hematoma, a doctor will likely monitor them and may recommend bed rest.
When bleeding is the result of a miscarriage, a doctor will perform a procedure called a dilation and curettage, to remove tissue.
An ectopic pregnancy may require surgery.
While breakthrough bleeding is usually not a cause for concern, speak to a doctor anytime bleeding occurs during pregnancy.
If a person bleeds between periods, their contraceptive method may be responsible. Or, they may have an infection. Consult a doctor if this bleeding happens frequently, is heavy, or otherwise causes discomfort.