In all likelihood, you’ve got your menstrual cycle down to a science. So when you miss your period, it can immediately trigger the pressing question “Am I pregnant?”

Maybe you’re trying to conceive, so you start to get your hopes up. Or maybe parenthood part of your plans, and you’re struck with feelings of impending doom.

Whatever the case, you grab a pregnancy test at the drugstore, take it, and wait nervously for those two blue lines to show up. But the test comes out negative… and you still haven’t gotten your period. What the heck is going on? Is everything OK?

Depending on when you took the test, you could get a false negative result. Home pregnancy tests aren’t always perfectly accurate — especially if you take them too soon after your missed period. Different brands of tests have different guidelines about timing.

Even if the test you bought claims to be accurate on the first day of a missed period, you’re better off waiting at least one more day. Your body needs to have a high enough level of the hormone human chorionic gonadotropin (HCG) for the test to detect.

Early in pregnancy, HCG levels double every few days. Since your ovulation date could be slightly different each month, it may take a week or two after conception to get a reliable pregnancy test result.

Wait several days, and if you still don’t get your period, take the test again. It’s best to take a pregnancy test first thing in the morning, before your urine has been diluted with fluids from food and water.

If the second or third test is negative, it’s time to look at other potential causes of your missed period. Amenorrhea (the scientific term for lack of menstruation) can happen for many reasons, and you may need to see a healthcare provider to get things back on track.

Here are eight possible reasons for a missed period and a negative pregnancy test.

If you gain or lose a significant amount of weight in a short time, it can mess with your hormones — and therefore your menstrual cycle. Your periods might become irregular or stop altogether.

People with eating disorders like anorexia or bulimia sometimes lose their periods as a result of these conditions.

If you think you or someone you know may have an eating disorder, contact the NEDA Helpline at 1(800) 931-2237, or instant message a representative through NEDA’s helpline chat.

High stress levels can also wreak havoc on your hormones. Try to get some rest, eat well, and remove as many anxiety triggers as you can.

You might also consider talking to a mental health professional to learn how to manage your stress in a productive way.

Have you been super sick recently with the flu, mono, or another condition that put you in bed watching movies for several days straight? It could potentially affect your menstrual cycle.

As long as you get back to your normal routine, your regular period should return within a month or so.

Your daily workout routine might help you with those #BootyGains, but be careful not to overdo it.

Excessive exercise can cause your metabolism to slow down as your body tries to conserve energy, and in some cases, your period may become irregular or stop altogether. This could also happen if you’re not eating enough to balance the daily calorie burn.

Some medications, like birth control, can cause changes in your cycle and cause your periods to lighten or stop over the course of several months.

If you recently started a new antidepressant, contraceptive, or any type of hormone replacement, talk with your doctor about why your period is MIA and whether it’s something to worry about.

Prolactin, the primary hormone that supports breast milk production, also stops menstruation.

New moms who are breastfeeding a child may have light periods or no periods at all. (Kind of a win, right?)

Some health conditions can mess with your menstrual cycle by changing the levels of common fertility hormones in your body.

If you think you might have polycystic ovary syndrome or another pelvic condition, talk to your doctor for further insight on diagnosis and treatment.

In rare cases, a fertilized egg can implant itself outside the uterus, causing something called an ectopic pregnancy that can’t be detected by a normal pregnancy test.

This requires medical attention ASAP, so look out for other symptoms such as:

  • sudden, sharp abdominal pain
  • abnormal bleeding
  • cramping in your lower back and pelvic area

If you notice these symptoms, call your doctor right away.

No period but still experiencing brownish discharge or light bleeding during odd times in your cycle? Several of the same issues we just covered could be causing this — birth control, pelvic conditions, weight changes, or stress.

Spotting can also happen due to ovulation, sexually transmitted infections, or (in rare cases) benign or malignant tissue growths. If the spotting is accompanied by fever, yellow or foul-smelling discharge, or acute pain, see your doctor.

Spotting could also mean you’re entering perimenopause, the stage when your body begins the transition to menopause. For most women, this happens between the mid-30s and 40s.

If you’ve already gone through menopause and are experiencing spotting, you should talk to your doctor about it.

When your hormones get out of balance, your cycle can change, and it may not get back to normal until you sort out the cause.

If you’re dealing with a temporary issue like stress or illness, or something prescribed by a doctor, like medication or birth control, there’s no need to be concerned.

But if you haven’t had a period in 3 months or more, or if your period happens less often than every 35 days, you should consult your healthcare provider.

It’s also a good idea to call your doctor if your period changes significantly — say, your bleeding gets a lot heavier or your cramps get way worse. In most cases, lifestyle changes or medication adjustments can help get your cycle back on track.

You are the expert on your own body, so it’s important to pay attention to your periods and bleeding patterns. During your annual OB/GYN visit (which you should definitely be scheduling, by the way!), talk with your doctor about any irregularities.

A consistent period is a good measure of overall health, so it’s worth monitoring your cycle for subtle changes from month to month.

But if you missed your period and the pregnancy test reads negative, and your menstrual cycle soon gets back to normal, you’re fine to just keep doing your thing.