Your body’s stress response system is rooted in a part of your brain called the hypothalamus.

When your stress level increases, your brain tells your system to flood your body with hormones that switch on your fight-or-flight mode. These hormones suppress functions that aren’t essential to escaping a threat, including those of your reproductive system.

If you’re under a lot of stress, your body can stay infight-or-flight mode, which can make you temporarily stop ovulating. This lack of ovulation, in turn, can delay your period.

Severe changes in body weight can screw with your period’s timing. Extreme increases or decreases in body fat, for example, can lead to a hormonal imbalance that causes your period to come late or stop entirely.

In addition, severe calorie restriction affects the part of your brain that gives instructions for the production of reproductive hormones. When this communication channel is disrupted, hormones can get out of whack.

Common in those who train for several hours a day. It happens because, whether intentionally or not, you’re burning way more calories than you’re taking in.

When you burn too many calories, your body doesn’t have enough energy to keep all its systems running. This can lead to a hormonal imbalance that throws off your menstrual cycle, leading to missed or late periods.

Periods typically go back to normal as soon as you lessen training intensity or increase your calorie intake.

‍Polycystic ovary syndrome (PCOS) is a set of symptoms caused by an imbalance of reproductive hormones. People with PCOS don’t ovulate regularly. As a result, your periods may be lighter than normal, arrive at inconsistent times, or disappear altogether.

Other PCOS symptoms can include:

• excess or course facial and body hair
• acne on the face and body
• thinning hair
• weight gain or trouble losing weight
• dark patches of skin, often on the neck creases, groin, and underneath breasts
• skin tags in the armpits or neck
• infertility

Many love the pill because it makes their periods so regular. But it can sometimes have the opposite effect, especially during the first few months of use.

Similarly, when you stop taking the pill, it can take a few months for your cycle to get back to normal. As your body returns to its baseline hormone levels, you may miss your period for a few months.

If you’re using another hormonal birth control method, including an IUD, implant, or shot, you might completely stop getting your period.

Perimenopause is the time leading up to  menopause. It typically starts in your mid-to late 40s. Perimenopause lasts for several years before your period stops completely.

For many, missed periods are the first sign of perimenopause. You may skip a period one month and be back on track for the following three. Or, you may skip your period three months in a row and find that it arrives unexpectedly, often lighter or heavier than you’re used to.

Early menopause, also known as premature ovarian failure, happens when your ovaries stop working before you turn 40.

When your ovaries aren’t working the way they should, they don’t produce enough oestrogen. As oestrogen levels drop to all-time lows, you will begin to experience the symptoms of menopause.

Late or missed periods may be an early sign. You may also experience hot flashes, night sweats, and trouble sleeping.

Other signs of premature ovary failure include:

• vaginal dryness
• trouble getting pregnant
• decreased sexual desire
• trouble concentrating

Your thyroid is a butterfly-shaped gland in your neck that produces hormones that help regulate many activities in your body, including your menstrual cycle. There are several common thyroid conditions, including hypothyroidism and hyperthyroidism.

Both hypothyroidism and hyperthyroidism can affect your menstrual cycle, causing irregularity, but hyperthyroidism is more likely to cause late or missed periods. Sometimes, your period may disappear for several months.

Other symptoms of a thyroid issue include:

• heart palpitations
• appetite changes
• unexplained weight changes
• nervousness or anxiety
• slight hand tremors
• fatigue
• changes to your hair
• trouble sleeping

Your period is generally considered late once it’s been at least 30 days since the start of your last period.

If your period is regularly late, make an appointment with your healthcare provider to determine the cause.