Missed or late periods happen for many reasons other than pregnancy.

Common causes can range from hormonal imbalances to serious medical conditions.

There are also two times in a woman’s life when it’s totally normal for her period to be irregular: when it first begins, and when menopause starts.

If you’ve had a missed period with a negative pregnancy test, here are 7 possible reasons for that:

STRESS
You already know stress can have a number of unpleasant effects, like headaches, weight gain, acne and other skin issues — and it can also affect your period.

When you’re under physical or emotional stress, your body produces the stress hormones adrenaline and cortisol.

Things like blood flow to the muscles and oxygen to the lungs increase (part of the “fight-or-flight” response you’ve likely heard of), while others, like digestion and the reproductive system, may stop temporarily in extreme cases.

When the reproductive cycle is delayed, so is your period.

ILLNESS
Being sick at the time you normally would ovulate can delay ovulation – and if you ovulate late, you’ll get your period late.

So if your period hasn’t arrived on schedule, think back a few weeks – were you under the weather?

YOU MAY HAVE POLYCYSTIC OVARIES
Polycystic ovary syndrome (PCOS) is caused when high levels of certain hormones stimulate your ovaries to produce lots of follicles.

None of the follicles mature enough to release an egg.

Because you haven’t ovulated, you don’t have a period either.

Other signs of PCOS include excessive hair growth on your face, chest and lower abdomen, acne, and a tendency to put on weight around your middle.

MAJOR WEIGHT LOSS OR EXCESSIVE EXERCISE
If your BMI rapidly dips below 18 or 19, you may start to miss periods.

This isn’t strictly based on BMI, though. Serious conditions like anorexia and bulimia can cause missed periods, but so can training for a marathon or some other major event that requires you to exercise more than usual.

Nature has a way of protecting you from getting pregnant if your body is under such extreme stress.

CONTRACEPTION
Some women who use a contraceptive implant (such as a Mirena coil), a contraceptive injection or, less commonly, the contraceptive pill (sometimes called the ‘mini pill’) may find their periods become irregular or stop completely.
Your periods should start again once you stop using these forms of contraception, although occasionally these effects can persist.

THYROID CONDITIONS
The thyroid gland is found in the neck.

It produces hormones that are released into the bloodstream to control the body’s growth and metabolism.
In some women, the thyroid gland can:
1. produce too much thyroid hormone – this is known as having an overactive thyroid gland or hyperthyroidism
2. produce too little thyroid hormone – this is known as having an underactive thyroid gland or hypothyroidism
Both hyperthyroidism and hypothyroidism can cause absent periods.

BREASTFEEDING
If you’re breastfeeding you may not see your period for some time, since prolactin — the hormone responsible for breast milk production — also suppresses ovulation.

Though a missed period can be emotional, try not to jump to conclusions until you find out what’s really going on.