Why Is My Period Late If I'm Not Pregnant?

by Robin Elise Weiss, Ph.D. Health Professional

Most women learn to track their menstrual cycle after she has her first period, known as menarche. While you may or may not be someone who obsessively counts days and tracks symptoms with a period app, you may still know instinctively when your period is late. Beyond pregnancy, there are several reasons why your period may be delayed or irregular.

What is a ‘normal’ menstrual cycle?

A normal menstrual cycle is usually described as 28 days, with three to five days of bleeding. Note that the days you have your period are included in the count of the menstrual cycle. The cycle begins with day one of bleeding.

There is a wide range of “normal” in a menstrual cycle. What is most important in predicting your period is what is typical for you. In general, as long as your cycle is between 24 and 38 days long, it is considered normal. It is also normal to bleed up to 8 of the days of your menstrual cycle. If you have a cycle that is shorter than every 24 days or longer than every 38 days, it may point to an underlying issue, and you should talk to your doctor or other practitioner about this irregularity.

Why is my period late?

Most people assume a late period means you are pregnant. Pregnancy stops the menstrual cycle because the uterine lining that is typically shed during your period is now needed to nourish a pregnancy. However, pregnancy is only one of the reasons that your period might be delayed.


Once you are in your mid-40s, you may notice that your menstrual cycles become irregular. This can cause a delay in your period. Irregularity is a precursor to menopause but can last years before your period truly stops. Your doctor or practitioner can help you with the associated symptoms of perimenopause; there are multiple treatment options available.

Issues with ovulation

Ovulation is the process in which an egg is released for fertilization every month. The hormones that help an egg mature and your uterine lining build and eventually slough off during your period are delicately balanced. The progesterone normally released during ovulation is what causes the period. Without ovulation (anovulation), and therefore progesterone, the uterine lining continues to build. If this happens, your doctor may prescribe a medication that can bring on your period. They may also try to determine the reason for the lack of ovulation. In some cases, anovulation is essentially a fluke and is not repeated. In other cases, there is an underlying cause that may need treatment.

One common cause of missed or delayed periods is polycystic ovary syndrome (PCOS). This condition is where the ovaries produce multiple cysts, interfering with ovulation and delaying or halting your menstrual cycle.

Early menopause, also known as ovarian insufficiency, can also lead to a lack of periods. Early menopause can be caused by medical treatment such as some chemotherapies or hormonal treatments, or other medical problems. This is something that your practitioner can run tests to see if you are in early menopause based on your hormone levels.

Birth control methods can halt your cycles

Some forms of hormonal birth control methods can cause you to have irregular periods. This is more common with methods like the birth control injection (Depo-Provera), hormonal IUDs, and birth control pills taken continuously without a break, meaning they intentionally stop your period. In these cases, a lack of period or an irregular period is not considered problematic, but it may concern you if you were not expecting it. Be sure to ask your doctor or other practitioner how your birth control method may alter your cycles.


Breastfeeding can also suppress your hormones, potentially stopping you from ovulating and having. This can last for many months, even past one year after you’ve given birth. This generally happens when you are nursing a baby exclusively, without supplementation. Once you decrease the amount of breastfeeding needed to delay your cycles, you will see a return of your period. Many women consider this a benefit of breastfeeding.

Pituitary tumors

Prolactinomas, or pituitary tumors that secrete prolactin, can also cause you to not have a period. These benign tumors can grow on your pituitary gland in your brain. The absence of a period is just one of the symptoms. This is screened for with a blood test of your prolactin levels. These tumors are fairly rare, occurring only in about 14 out of 100,00 people per year.

Bottom line

There are a variety of reasons that your period may be delayed. If you think your period should start and it doesn’t, wait a few weeks. If you don’t have a positive pregnancy test or other obvious, expected reason within that time frame, you should call your doctor. They can do a physical exam and order some blood work to help you figure out what’s up with your menstrual cycle.


Absent or irregular periods (Beyond the Basics).
Up-to-Date. Updated June 14, 2017. Accessed February 2018.

This is an update to an article originally written by HealthCentral contributor Merely Me.

Robin Elise Weiss, Ph.D.
Meet Our Writer
Robin Elise Weiss, Ph.D.

Robin Elise Weiss, Ph.D., LCCE, CLC, AdvCD(DONA) is a childbirth educator, doula, founder of Childbirth.org, and the award-winning pregnancy and parenting author of “The Complete Illustrated Guide to Pregnancy” and more than 10 other books. Between her nine children, teaching childbirth classes, and attending births for more than two decades, she has built up an impressive and practical knowledge base. You can follow Robin on Twitter @RobinPregnancy, Instagram @Robineliseweiss, and Facebook @childbirthtrainings.