So here are some possible reasons for a wonky period — whether it’s missing, late, early, or just a little ~different~. 1. OK, are you sure you’re not pregnant? This is obviously this first thing you’ll want to cross off the list, even if you’ve been super careful or using birth control. “Half of all pregnancies in the U.S. are unplanned,” Dr. Mary Jane Minkin, clinical professor of obstetrics and gynecology at Yale School of Medicine, tells BuzzFeed Health. And it’s not just late or missing periods that could signal pregnancy. You can also get irregular bleeding at the beginning of a pregnancy, which many people mistake for an early period, says Minkin. So if your period is early/late/missing and it’s even remotelypossible that you could be pregnant, go ahead and pee on a stick. 2. Maybe you’re just really stressed. Fun fact: Ovulation actually starts in the brain with the pituitary gland. Things like stress, anxiety, travel, moving — those can all throw off the connection between the pituitary gland and your ovaries, Dr. Lauren Streicher, associate clinical professor of obstetrics and gynecology at Northwestern University and author of Sex Rx, tells BuzzFeed Health. And when the ovulation cycle gets screwed up, so does your period. BUT stress will not affect your period if you’re taking hormonal birth control. That’s because contraception like the pill, ring, implant, and IUD all work to regulate your cycle. So if you’re on hormonal birth control, ovulation wouldn’t be giving you a monthly period — your birth control would be, says Minkin. 3. Did you recently start, stop, or change birth control? Birth control can definitely screw with your period — usually in a good way. For most people, it can eventually make your period way lighter, especially on a low-dose pill or the hormonal IUD, says Minkin. So if your period is slowly disappearing while you’re on birth control, that’s a reason to celebrate, not freak out. Or you might notice your period get heavier on certain methods — particularly with the copper IUD, says Streicher. 4. Or maybe you kinda fucked up your birth control this month. Maybe you skipped a pill. Or five. Some people may get breakthrough bleeding (which could look like an early period) if they miss pills — especially if they’re on a very low-dose pill, says Minkin. 5. Maybe you were sick recently. Colds, viruses, and the flu can mess with your cycle the same way stress can, says Streicher, but only if you’re not on hormonal birth control. And if you’re on low-dose birth control, taking certain antibiotics may result in breakthrough bleeding, which could look like an early period. This is because antibiotics can alter the levels of estrogen slightly. It’s usually not enough that you need to worry about the pill’s effectiveness, but it could be enough to give you some breakthrough bleeding. 6. Or you recently lost or gained a lot of weight. People who exercise a lot (athletes, gymnasts, or someone training for a marathon, for instance), might end up missing periods, especially if they have very low body fat, says Minkin. But sudden weight gain can also affect ovulation, since too much body fat can lead to increased production of estrogen. 7. It might be your thyroid. A common cause of irregular periods is a thyroid condition. Hyperthyroidism typically causes lighter periods (or none at all), while hypothyroidism can lead to heavier bleeding, says Minkin. So if you have any other symptoms to go with your period problems, definitely tell your doctor about that. 8. Or it could be a side effect of literally any other chronic illness. Polycystic ovary syndrome and endometriosis are two conditions that can definitely affect your periods, typically making them heavier, longer, or irregular. But pretty much any illness, condition, or surgery could possibly throw off ovulation and, in turn, screw with your period, says Streicher. So if you know you have a chronic illness, it’s worth talking to your doctor about how that might affect your flow. 9. It’s also maybe kinda possible that you’re perimenopausal. Comedy Central Random mid-month bleeding usually isn’t your period. But it could be lots of other things. If you’re on birth control, it could be breakthrough bleeding, which could happen if you miss a pill, take your pills continuously, or take certain antibiotics. And if you’re not on birth control, it’s possible that irregular bleeding could be a sign of an early miscarriage, says Streicher. Or you might actually be bleeding after sex, says Minkin, which could be a sign of a cervical polyp, infection, dryness, or a tear. Irregular bleeding could also be a sign of pelvic inflammatory disease (PID) from an untreated chlamydia or gonorrhea infection. So if you have any other symptoms or the bleeding persists, check in with your doctor. 10. Or maybe that’s not actually an early period at all — it’s some other kind of bleeding. 11. Or…Sometimes your body does some weird shit and no one really knows why. “We see this in women who are trying to get pregnant — we don’t always have an explanation,” says Streicher. The bottom line: If you have one wonky period, you probably don’t need to freak out. Whether it’s late, early, heavier, lighter, or just missing entirely, one fucked-up period isn’t usually anything to worry about. “The first thing is to make sure you’re not pregnant,” says Streicher. “Once we have eliminated that, usually what we say is ‘chill.’” But if you’ve gone a few months without a period, if you’re having consistently screwy periods, or if you’re experiencing any other weird symptoms, definitely check in with your doctor about that. Source