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late period clue app

Illustration by Emma Günther

Reading time: 5 min

Why is my period late?

Reasons for a late period

Top things to know about why your period might be late: 

  • Menstrual cycles can vary in length by up to 7–9 days

  • There are several health-related reasons why your period could be late

  • Unpredictable periods are common and expected around menarche and menopause 

  • If you’ve had unprotected sex and your period is 10 or more days late, you should take a pregnancy test and talk to a healthcare provider regardless of the result

  • Speak to a healthcare provider if you haven’t had a period for more than 90 days

  • Tracking with Clue can help you learn when to expert your period

Expecting a period to come that doesn’t can cause your stomach to drop. Your mind starts racing. You try to remember everything you’ve done in the past month that could have contributed to this. Questions flood your mind: “Did I have sex? When did I? Did we use protection? What if my birth control didn’t work? Am I pregnant?” Before you start to spiral, take a deep breath and read this.

Your body is not a clock. The number of days between your periods may vary, especially if you are a teenager, breastfeeding or nearing menopause. Stress, travel, diet, illness, and medication (including birth control) can also affect your cycle. As an adult, your menstrual cycle can vary in length by up to 7–9 days (1).

How to know if your period is late

It can be hard to know if your period is late if you don’t know the average length of your cycle or when your last period was. If you think your period is late, get out a calendar and try to remember the first day of your last period (2). If you can do this for the past three periods it will be helpful. With this information, you can count from the first day of one period to the first day of the next period and figure out how many days you usually have between your periods. You may already do this with and that’s why you know your period is late. 

What to do if your period is late

If you’ve had sex that could result in pregnancy or if sperm could have reached your vulva during another type of sex or intimacy and your period is 10 or more days late, you should take a pregnancy test. Regardless of the results of the pregnancy test, you should talk with your healthcare provider (1). There are reasons other than pregnancy that your period may be late. If you have not had sex or participated in any type of sexual intimacy but you have not had a period for more than 90 days, you should speak to a healthcare provider (3). They can help you sort out what may be making your periods unpredictable.

Top reasons why your period might be late

Your period may be late for several health-related reasons (4,5,6,7): 

  • Stress

  • Obesity 

  • Very low body weight/extreme exercise

  • Eating disorders 

  • Polycystic Ovarian Syndrome (PCOS)

  • Birth control 

  • Chronic conditions (such as diabetes)

  • Peri-menopause

  • Thyroid issues

  • Hormone changes related to medications or birth control

  • Breastfeeding

  • Pregnancy

How soon will a pregnancy test work?

Pregnancy tests work by checking your blood or urine for a hormone called human chorionic gonadotropin (hCG). This hormone has to be at a certain level to be detected by a pregnancy test (8). The earlier you take a test, the less accurate it may be. It is recommended to take a pregnancy test 1-2 weeks after your missed period (9). If you don’t want to wait that long, you can consider taking it 2 weeks after your last unprotected sexual encounter. If you get a negative result at first and you still haven’t had your period, you can take another pregnancy test a few days later or repeat the test if you’re unsure you took the test correctly (9). Seek advice from your healthcare provider if you’re unsure of your test result. 

What do I do if I’m pregnant?

If your pregnancy test is positive, you will want to make a plan. A first step can be meeting with a trusted healthcare provider. If you want to keep the pregnancy, it is recommended to start taking prenatal vitamins as soon as possible to help maintain a healthy pregnancy (9). If you are unsure if you want to be pregnant or if you want to end your pregnancy, a healthcare provider can guide you through the process. There are online resources that you can use to find both pregnancy care and abortion services

If you are transgender or nonbinary, there are many organizations worldwide that can help you to find a trans-friendly OB/GYN.

How to make tracking your period easier

Understanding your menstrual cycle baseline, or what’s typical for you is important. It can be an indicator of your body’s functions and your overall health. It’s also helpful to know details such as: 

  • The number of days you bleed

  • How heavy or light your bleeding is

  • Any pain you experience leading up to and during your periods

  • How you feel emotionally

  • The amount of sleep you get

  • Medications and birth control you take 

  • Your energy level, sex drive, and sexual encounters

You should consider contacting a healthcare provider if you experience any sudden changes in your period or menstrual cycle. If you haven’t had a period in more than 90 days, you should speak to a healthcare provider (10). They can help you figure out what may be happening by asking some questions and maybe running some lab tests. Being able to share details about your menstrual cycle can help make the process quick and efficient. 

A late period can make you feel emotional, but try not to jump to conclusions until you find out what’s really going on. It’s completely normal for the length of your menstrual cycle to vary sometimes—maybe it’s nothing at all.

Download Clue to track your period, your menstrual experiences and more.

This article was originally published July 13, 2017.

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Live in sync with your cycle and download the Clue app today.

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