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Is your menstrual cycle usually as regular as clockwork, but has your period suddenly come early or late? You are likely to be worried that something is wrong — especially if you have recently had unprotected sex as well, and pregnancy and sexually transmitted diseases are in the back of your mind. 

Let's examine what could have caused your sudden menstrual cycle irregularities. 

Age-Related Hormonal Imbalance

A hormonal imbalance is one of the most common causes of menstrual cycle irregularities. 

If your hormones are out of whack, something that often happens during puberty and again as a woman approaches the menopause, your menstrual cycle may suddenly become longer or shorter. The severity of your menstrual flow can also change. Women who are not either going through puberty or at an age where they can expect to be dealing with perimenopausal symptoms should seek medical help if this happens regularly. 

Are You Using Hormonal Contraceptives?

If you have recently started using a hormonal contraceptive method such as the birth control pill or the Mirena intrauterine system, your periods may become irregular and your flow may be lighter or heavier than before. It is also possible to experience spotting (light blood loss) between periods. 

Stressed Out?

Here's one for everyone who is asking why their period is early or late (but not absent) after they have recently had unprotected sex — stress can impact your hormonal balance. The possibility of an unwanted pregnancy is certainly stressful enough to make this happen, and the more stressed you are, the more likely it is to impact the timing of your period. 

Medical Conditions That Can Lead To Irregular Menstrual Periods

Can none of the factors above logically explain your suddenly irregular period or periods? Other causes of an irregular menstrual cycle include:

  • Polycystic Ovary Syndrome. This syndrome, characterized by polycystic ovaries and an excess of hormones called androgens, affects both your reproductive system and your metabolism. It often leads to irregular periods during which you do not ovulate, as well as excess hair growth and weight gain. 
  • Weight fluctuations, including those caused by eating disorders. Extreme underweight and overweight can both lead to irregular periods. 
  • Excessive exercise. 
  • Uterine fibroids. 
  • A miscarriage or early pregnancy spotting, which a woman who did not know she was pregnant may mistake for a menstrual period. 
  • An overactive thyroid (hyperthyroid) or underactive thyroid (hypothyroid). Hypothyroidism will cause such symptoms as fatigue and unexplained weight gain, along with depression and muscle cramps. Hyperthyroidism, meanwhile, causes unexplained weight loss and feeling jittery. Both can lead to menstrual irregularities. 

What Should I Do?

If your period comes early or late once in a while, there is no particular need to be worried — especially if you have been stressed recently, or you have recently started using hormonal contraception. 

Women who have recently had unprotected sex and who do not want to be pregnant are always wise to take a pregnancy test if their period comes late. They should also be tested for sexually transmitted diseases, where relevant. 

Have your menstrual cycles been irregular for a while, and are you worried? Checking in with your doctor is advisable. 

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