Why is My Period Late?

There are a few things that can cause a late period. Pregnancy is one of these, but it is by no means the only thing that can affect your cycle. In this post, we’ll breakdown the common reasons for late periods, from stress to weight loss and more. Read on to find out how your cycle might be affected and how tracking ovulation can teach us all more about our bodies.

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Late periods and pregnancy

In the movies it’s become a cliche, a woman misses her period and you know she must be pregnant. While a late period is indeed one of the signs of early pregnancy, there are also so many other things that can influence the regularity of your cycle and push back your period. 

To get pregnant you have to have unprotected sex within your fertile window, which is in fact only 6 days in any menstrual cycle. 

How early can you tell if you are pregnant?

This varies from woman to woman, with some noticing symptoms from as early as a week after conception, while others may take several months before they notice a change. Many won’t experience symptoms in early pregnancy at all, though some may have an implantation bleed.

To make it more confusing, some symptoms of early pregnancy, such as tiredness or breast tenderness, are also associated with PMS, so it can be tricky to tell if you are pregnant or if your period is just a few days late.

If you think you might be pregnant, we recommend taking a pregnancy test on the first day of your missed period. If this is negative and you still think there is a chance you are pregnant, test again after 48 hours.

Of course, you should speak to a healthcare professional if you have concerns around your missed menstruation. In the meantime, we’ll put pregnancy aside and look at some other reasons for late periods.

Hormonal birth control affects your cycle

Most hormonal birth control works by stopping ovulation. The monthly bleed you get if you take the birth control pill isn’t actually a period, it’s something called a withdrawal bleed. Taking synthetic estrogen and/or progesterone has an impact on the way our cycles behave and the thing is, even after you stop taking the pill, have the implant removed, or discard the last NuvaRing, those hormones stay in your body. In fact, it can take up to a year for your cycles to return to normal after you stop taking hormonal birth control.

If you use emergency birth control such as Plan B, you are also going to see an impact on the length of your cycle too. This is because the estrogen in the morning after pill delays ovulation, so you will likely see this reflected in the pattern of your cycle.

Your mood can affect your cycle

Stress and the menstrual cycle are linked. If you’re feeling anxious or worried it can have a knock-on effect and cause a late period, which in turn can cause us to feel more anxious… Typical right? A little stress is normal, but a lot can be bad for our health. It can be easier said than done, but try to make room for relaxation in your routine. If you feel like your everyday life is being affected by stress, consult your healthcare professional. 

It’s not just stress that can impact the cycle, other lifestyle alterations such as a change in exercise routine or diet can also delay your period. So if you’ve been hitting the gym more than usual, or have recently cut calories, these might also be responsible for a shift in your menstrual pattern.

Weight and hormones can cause late periods too

As with a change in diet or exercise, a rapid change to your weight can also cause you to have a late period. Both extreme weight gain or weight loss can make you late. With weight loss, your body might reduce the production of the hormones that trigger ovulation. While weight gain can also impact the cycle, causing the production of excess estrogen, which in turn affects the cycle. If you are overweight or underweight your doctor may refer you to a dietitian for advice.

Some conditions can affect your cycle 

Certain conditions such as polycystic ovary syndrome (or PCOS) and endometriosis can affect the regularity of your cycle or cause anovulatory cycles (cycles with no ovulation). An over or underactive thyroid may also affect your cycle patterns. If you have frequently late periods and other symptoms such as severe period cramps or fatigue, discuss your symptoms with your doctor - there are treatments available for cycle conditions. 

Age is more than a number

The regularity of our flow isn’t random, it’s actually linked to our biological clock. During our fertile years, we will likely see a shift in the length of our cycles. Around puberty, when we first start to menstruate, irregular periods are very common, but often our cycles become more regular in time.

While our cycles tend to get shorter as we get older, around menopause we can see a similar shift as after puberty, with our cycles becoming irregular again. During menopause, it’s common to get late or early periods, before the bleeding stops altogether. 

Get to know your unique cycle

We hope you’ve learned some useful info on the reasons for late periods and how our environment and our biology can affect our bodies. Ultimately, we’re all different and our cycles are no exception. However, it’s much easier to spot changes when we understand the pattern of our own unique cycles and tracking your cycle lets you do just that.

Some period tracking apps use a variation of the rhythm method to calculate where you are in your cycle, this is flawed in that it assumes your cycle is 28-days long, a common myth and one we dispelled in our recent scientific study.

Our technology is different. Natural Cycles is the first FDA Cleared and CE Marked birth control app. Our algorithm uses temperature data to learn the pattern of your unique cycle and notify you of your own specific fertile window that’s specific to your own ovulation. You can then use this science to either plan or prevent pregnancy completely hormone-free. Why not find out if Natural Cycles could work for you?

Discover the world's first birth control app.

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Written By

Jennifer Gray

A writer with a passion for women’s health, Jennifer Gray has years of experience writing about various reproductive health topics including birth control, planning pregnancy, women’s anatomy, and so much more.

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Scientifically Reviewed

Jack Pearson

With 10 years of experience working in the field of fertility, Jack Pearson is Natural Cycles’ in-house expert. As Medical Affairs Manager, he dedicates his time to conducting groundbreaking research and educating healthcare professionals.