We can track our periods on a calendar the old-fashioned way and we have clever apps that help us track our periods, our symptoms and other factors of our cycles and we can learn our bodies to know what’s happening.

However, sometimes no matter how much we have tracked, logged, marked or noted our cycles, our periods can still surprise us a few days early, or leave us wondering where they are by showing up late. So why does this happen & what causes it?


Knowing our cycles and being more familiar with our menstruation is starting to become more talked about and understood. We’re learning the phases of each cycle more, and more information and studies are finally being available on periods and the menstrual cycle.

Everyone’s menstrual cycle is different. Your cycle starts on the first day of your period and ends on the first day of your next period. A typical cycle lasts anything between 21 to 35 days. So, the number of days spent bleeding can also vary person to person. Most people bleed for between 2 to 7 days. This can fluctuate, but most adults stay continuous from period to period in terms of their length of bleed.

Periods can be delayed by any number of days and for several reasons. If your next cycle starts from 28 days +/- 7 days from the first day of your last menstrual cycle, then it is considered a normal cycle. If a delay of 10 days occurs, this is not considered to be normal and may require some evaluation.



PUBERTY can cause your periods to be irregular. In the first few years after you get your period, the hormones that cause puberty and you beginning to get your period can be irregular. This means that the number of days between your periods may be shorter or longer than average. This is completely normal and as your teenage years progress your hormones will settle and become more regular, as will your periods.

Period underwear is great for teens experiencing their periods for the first time, especially while they’re a little irregular. You can read more on Teens periods & period underwear in our recent article


MAJOR WEIGHT FLUCTUATIONS can be an affect of early, late or missed periods. Rapid weight loss is usually the most influential on period irregularities. This can happen with extreme dieting, gastric surgery or eating disorders.

When the body enters starvation mode due to extreme weight loss, it reserves energy for the body’s essential functions like breathing, brain function & nerve function. Your body stops producing reproductive hormones due to conserving energy which leads to period irregularities, and in some cases, periods can stop all together.


STRESS is a common factor in our busy lives, but this can have a huge effect on our menstrual cycle. Severe stress can interfere with & disrupt hormone levels, causing irregular periods. If you experience high anxiety, are going through a very stressful time or traumatic event this can throw your hormones off and affect your menstruation.

CHANGES IN YOUR ROUTINE are understandable to then throw your periods out of whack! Some research suggests that people who switch between day and night shifts, like nurses & doctors often experience irregular periods. Switching and moving between time-zones can also have a similar effect.

Researchers don’t know exactly why this happens, but it may be related to a disruption in your circadian rhythm affecting your hormones. This may in turn, disrupt the sleep hormone melatonin.

Wearing period underwear when it’s due or the few days before can keep you protected and in control just in case!


HORMONAL BIRTH-CONTROL affects your reproductive hormones & periods intentionally to directly control ovulation & menstruation.

If you’re taking birth control pills, the timing of your next period will depend on when you started taking the pills through your cycle, and whether your birth control takes a break. Depending on when you took your last pill, whether you missed a day or two or what day you had your last one, this can affect the day you start you ‘period’. Periods are known to be lighter on hormonal birth control due to the intended effect they have.

Other hormonal birth control options, like intrauterine devices (IUDs) can cause menstrual irregularities for the first two or three months, including irregular periods.


PCOS (Polycystic Ovary Syndrome) is a common condition which is caused by an imbalance of hormones. It affects 1 in 10 females & menstruators of child-bearing age. It often goes undiagnosed, and many people don’t know that they have it until they have difficulty conceiving. PCOS can cause your periods to come early or late or be irregular in length or flow. It can also cause you to miss a period entirely.


DIABETES when undiagnosed or not properly managed can affect your whole body, including your periods. When un-managed blood sugar levels are chronically higher than normal, they can disturb the hormone balance and periods, as well as affecting your weight management which can then influence your periods. A study in 2011 found that many people diagnosed with Type 2 Diabetes had experienced irregular periods in the months & years preceding their diagnosis.


THYROID hormones are essential to several body functions including menstruation and metabolism. It is thought that 1 in 8 females will develop a thyroid condition in their life. Thyroid conditions cause the body to make more or less thyroxin than it needs. Symptoms vary depending on whether a thyroid is under-active or overactive, causing early menstruation, as well as lighter or heavier periods than expected.


IMPLANTATION BLEEDING is not actually an early period, but it could be confused as one. Implantation occurs when the fertilised egg attaches to the lining of the uterus. Usually, one to two weeks after conception.

Implantation doesn’t always cause symptoms, sometimes it goes unnoticed until a missed period; however, when symptoms do occur, they can include light bleeding or cramping. Bleeding is typically lighter than a normal period and doesn’t usually require any protection or period underwear. But if you’re unsure light protection period underwear are a great solution.



There can be other reasons that your period is early or late. If your body is usually very regular and you start noticing irregularities, it is always worth checking with your doctor, especially due to certain conditions being more serious than others when connected to an early, late or irregular period.

If you’re unsure if you’re early or late, you can use a calendar method or try a period and cycle tracker app, this can help you to see what’s regular for you and give you insights into your cycle and symptoms.


If your period is arriving off schedule sometimes, wearing light protection period underwear on the days before your period is due will provide the reassurance you need. You’re then ready and protected if it does come early - it won’t catch you off guard, but you’re not having to use single-use plastic disposable panty liners or spending the days worrying if you’ve started.

You can also safely sleep in period underwear in case you’re expecting your period may arrive during the night; then there’s no worry of stained sheets or undies.  

This article is meant for informative purposes and is not for use as diagnosis. If you’re concerned about a medical condition, please consult your doctor or a health care provider











Leave a comment

Please note, comments must be approved before they are published