If you feel like you can usually predict your period with military precision—or at least generally know when you can expect it to begin and end—breakthrough bleeding might throw you for a loop. Allow us to help you out if you’re now staring at your screen like, Wait, what is breakthrough bleeding, exactly? Breakthrough bleeding is spotting that happens between your regular periods. It can be pretty common and is often nothing to worry about, Jacques Moritz, M.D., an ob-gyn at New York-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 the most common breakthrough bleeding causes that people experience. They might give you an idea of what’s up before you go in to see the doctor.
1. You recently started a new birth control pill.
Spotting during the first three months after going on a new birth control pill is considered fairly normal, 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. Some gynecologists think that generics may not perfectly match brand-name formulations and that the slight difference may be enough to cause breakthrough bleeding. The United States Food and Drug Administration (FDA) says all generic drugs work the same as their brand-name counterparts but allow for a slight, natural variability that 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 a pill you’ve taken for longer than that, ask your ob-gyn about switching medications if it’s really bothering you.
2. You’re taking a very low-dose birth control pill.
Many of the newer generations of lower-hormone birth control pills have either very little estrogen or no estrogen at all, relying instead on progestin to regulate your cycle. While many people like these formulations because they experience fewer side effects overall, the super-low hormone 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 and what side effects you can expect if you make the jump.
3. You have an IUD.
Similarly to the pill, a hormonal IUD can cause breakthrough bleeding at first, usually 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’re ovulating.
Some people spot during ovulation because the downswing in hormones can cause a little uterine lining to break down too early, 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.
5. You’re perimenopausal.
Depending on your age, changes in your menstrual cycle are likely to indicate that your body is nearing menopause, which usually begins between ages 45 and 55. The phase before menopause, called perimenopause, can last for several years as hormone levels begin gradually shifting, according to the American College of Obstetricians and Gynecologists (ACOG). Along with periods that are lighter or heavier, shorter or longer, more or less frequent, you may experience breakthrough bleeding during hormone dips.
6. You’ve recently had sex.
Friction from vaginal intercourse can also cause breakthrough bleeding, especially if your vagina wasn’t lubricated enough (because there wasn’t enough foreplay, enough lube, et cetera). If you experience persistent vaginal dryness, it can compound this issue. Vaginal dryness can occur for lots of reasons, including childbirth, taking certain cold medications, and being in perimenopause or menopause. Perimenopause and menopause make you more likely to experience vulvovaginal atrophy, which is a reduction in estrogen that causes symptoms including irritation, soreness, urinary frequency, incontinence, and vaginal dryness. In the event that vaginal dryness during sex is the cause of your spotting, there are over-the-counter vaginal moisturizers that might help you find some relief, and you can always try to find a lubricant that works for you. If nothing is helping, your doctor might be able to offer more guidance.
7. You’re about to become pregnant.
Implantation bleeding is one of the earliest signs of pregnancy, occurring in up to 25% of pregnant people, according to 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.
8. You had vaginal intercourse while pregnant.
During pregnancy, the cervix gets very sensitive, and if it’s irritated during penetrative sex, 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 says. It doesn’t mean anything has happened to the baby—having penetrative sex doesn’t harm the fetus.
9. You’re pregnant and have a subchorionic hematoma.
A subchorionic hematoma 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 it doesn’t. In any case, it’s painless and very common, Dr. Moritz says. These usually aren’t a major cause for concern, and research isn’t really conclusive about whether or not subchorionic hematomas definitively increase a person’s risk of miscarriage or how factors like the size of the hematoma and when it occurs may influence that risk.
10. 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 polyps, and cervical polyps. Localized pain to varying degrees may come along with all of these, along with other symptoms, but it really depends on what you’re dealing with. Bleeding doesn’t necessarily occur with all of them. For example, it’s much more common to see bleeding with uterine polyps than with ovarian cysts, Dr. Moritz says.