In an ideal world, women would bleed out of their vaginas on a totally predictable schedule. (Well, okay, not really, but you know what we mean—in a more ideal world.) In reality, though, spotting and breakthrough bleeding is extremely common. There are plenty of things that can cause you to bleed off-cycle, and many of them are nothing worth freaking out about. For instance, spotting is often related to early pregnancy or the birth control pill, and it’s typically harmless as Jacques Moritz, M.D., an ob/gyn at NewYork-Presbyterian and Weill Cornell Medicine, tells SELF. Sometimes, though, breakthrough bleeding may be a sign of a medical issue that requires evaluation and treatment.
That’s why we’re going to make the blanket recommendation that if you are seeing bleeding between periods and aren’t sure why—especially if it’s new or accompanied by pain or other symptoms—you should get in touch with your primary care physician or ob/gyn so they can help you figure out what’s going on. In any case, here are some of most common reasons people experience spotting and breakthrough bleeding.
1. You recently started a new birth control pill.
Spotting during the first three months after going on a new birth control pill is par for the course, Dr. Moritz says. "It may take three months for your body to get used to the medicine and the lining of your uterus to adjust to it."
Spotting can also occur when you switch from a brand name to a generic, Dr. Moritz says. Gynecologists suspect that generics may not perfectly match brand-name formulations, and that the slight difference may be enough to cause breakthrough bleeding. The FDA says all generic drugs work the same as their brand-name counterparts, but allows for a slight, natural variability. (But it won't change the main function of the drug.) If after three months on a new pill you're still spotting, or you suddenly start spotting on your current pill, ask your ob/gyn about switching medications.
2. You’re taking a very low-dose birth control pill.
Many of the newer generations of lower hormone birth pills have either very little estrogen or no estrogen at all, relying mostly on progestin to regulate your cycle. While many people like these formulations because they experience fewer side effects, the super-low dosage makes breakthrough bleeding more likely, even when you've been using the same pill for a while. "The pill is making the lining of the uterus so thin that the little blood vessels are fragile and just break because they don’t have enough hormones for support," Dr. Moritz explains. If the spotting bothers you, ask your ob/gyn about switching to a higher dose pill.
3. You have an IUD.
Similarly to the pill, a hormonal IUD can cause breakthrough bleeding at first—for up to three to six months after insertion. When it comes to the copper IUD, irregular bleeding (and heavier, more painful periods) is relatively common and can go on for quite a while. As SELF previously reported, this is because the device can irritate and inflame the uterus. Although doctors generally recommend giving your body six months or so to adjust, talk to your ob/gyn if you’re miserable.
4. You have an STI.
While gonorrhea and chlamydia are usually asymptomatic—one of the reasons regular STI screening is so important—they can both cause vaginal bleeding (along with other symptoms), especially if the infection is left untreated and allowed to spread throughout the reproductive system. Endometritis (inflammation of the endometrium) and cervicitis (inflammation of the cervix) can occur, as well as pelvic inflammatory disease (PID), which can cause complications like permanent damage to the fallopian tubes and fertility issues. (Although gonorrhea and chlamydia are the most common infections associated with PID, according to the Mayo Clinic, other types of bacteria can cause it too.)
5. You're about to become pregnant.
Implantation bleeding is one of the earliest signs of pregnancy, occurring in up to 25 percent of women, according to the American College of Obstetricians and Gynecologists (ACOG). One to two weeks after fertilization, when the fertilized egg implants in the uterine lining, a very small amount of blood may flow from the uterus and out the vagina. "It's just a little spot, not a lot," Dr. Moritz says. You may experience cramps as well.
6. You're pregnant and having a subchorionic hematoma or hemorrhage.
This is essentially a blood clot that can occur when the outermost membrane surrounding the embryo (the chorion) separates a little from the uterine wall, allowing some blood to pool in that space between the two. Sometimes, that blood flows out of the vagina, but sometimes not. In any case, it’s painless and very common, Dr. Moritz says. Usually everything is fine, though depending on factors like the size of the hematoma, the mother's age, and the age of the fetus, they can sometimes come with a slightly increased risk of miscarriage, Dr. Moritz says.
7. You had vaginal intercourse while pregnant.
During pregnancy, "the cervix gets very sensitive, so when the penis touches it, it can bleed a lot," Dr. Moritz says. Additional blood vessels are developing there, according to ACOG, so bleeding a little after intercourse is no big deal. "It's totally fine," he reassures. It doesn't mean anything has happened to the baby—a penis can't actually get past the cervix and harm the fetus.
8. You're having a miscarriage or ectopic pregnancy.
Though bleeding during pregnancy is common and usually harmless, especially in early pregnancy, there are a few worst case scenarios you should be aware of. Bleeding is the first sign of a miscarriage, Dr. Moritz says, which occurs in about 10 percent of known pregnancies, according to ACOG. Cramping may also occur.
Bleeding is also the first sign of an ectopic pregnancy, as SELF previously reported, It occurs when the egg implants somewhere other than inside the uterus, almost always the fallopian tubes. While ectopic pregnancies are rare, they can become life-threatening if tubal rupture occurs, so seek medical care immediately so they can do a sonogram.
9. You’re ovulating.
Some women spot during ovulation because the downswing in hormones can cause a little uterine lining to break down too early, as SELF previously reported, causing light bleeding. If your mid-cycle bleeding is accompanied by one-sided pain, you might be dealing with mittelschmerz. This type of ovulation pain occurs when the follicle ruptures and releases its egg, according to the Mayo Clinic.
10. You’re perimenopausal.
Changes in your menstrual cycle are the hallmark indicator that your body is nearing menopause. The phase before menopause, called perimenopause, can last for several years as hormone levels begin gradually shifting, according to ACOG. Along with periods that are lighter or heavier, shorter or longer, more or less frequent, you may experience breakthrough bleeding during hormone dips.
11. You have a gynecological cancer.
Although many women with gynecological cancer don’t experience any symptoms, especially early on, abnormal vaginal bleeding is often one of the first signs that you have cervical, ovarian, uterine, vaginal, or vulvar cancer, according to the CDC. Although cancer is unlikely, it’s a good idea to see your doctor to rule out. This is especially true if you are postmenopausal, Dr. Moritz says, because common causes of bleeding like the pill or pregnancy are off the table, raising the odds it could be cancer. "Any time after menopause, any spotting, even a drop, has to be investigated," he says.
12. You have noncancerous growths on your ovaries, uterus, or cervix.
There are a number of abnormal but typically benign growths that can occur on your reproductive organs, including ovarian cysts, uterine fibroids, uterine/endometrial polyps, and cervical polyps. Local pain to varying degrees may come along with all of these, although the occurrence of other symptoms varies. And bleeding doesn’t necessarily occur in all of them. For example, it’s much more common to see bleeding with endometrial polyps than with ovarian cysts, Dr. Moritz says.
Although bleeding from any of these growths is pretty normal, your doctor may want to run tests or remove them even if they’re benign, because in addition to pain and other symptoms, they can cause complications like fertility issues.