In short

A stopped period in a teenager is most often caused by the natural irregularity of early cycles, but stress, rapid weight change, over-exercising, and conditions like Polyendocrine Metabolic Ovarian Syndrome (PMOS) can also be behind it. 

If her periods were previously regular and have now stopped for three months or more, a doctor visit is a sensible next step. 

If periods were never regular, a pause of several months is still common in the first two years after they start.

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Why do periods stop in teenagers?

There are several common reasons why a teen's period might stop or become very infrequent. Some of these are straightforward and self-resolving; others need a little more attention.

The most frequent causes include:

• The natural irregularity of the early stages of puberty, especially in the first two years after periods begin
• Significant stress, such as exam pressure or family upheaval
• Rapid weight loss or being underweight
• Exercising very intensively, particularly in competitive sport
• A hormonal imbalance or a condition such as PMOS or an underactive thyroid

Could it just be her cycle settling?

If her periods have only been going for one to two years, some variation is expected. 

The NHS explains that irregular periods are common during early puberty, and it can take time for the hormonal system to establish a consistent rhythm.

A gap of several months does not automatically mean something has gone wrong.

When does it become a pattern worth investigating?

It may be worth seeing a doctor if:

• Periods have stopped for three months or more after previously being regular
• Three or more periods have been missed in a row at any stage
• The missed periods come alongside other changes such as unexplained weight gain or loss, increased tiredness, or new hair growth on the face or body
• Your sporty daughter has lost her period during intense training

These can be signs of a hormonal condition that may respond well to early treatment.

Can stress and weight affect her cycle?

Yes, both are well-recognised causes of disrupted periods in teenagers. Cortisol (the body's main stress hormone) can interfere with the reproductive hormones that trigger ovulation.

Very low body weight, or losing weight quickly, sends a signal to the body that it is not in the right condition to support a pregnancy, and periods can stop as a result. 

This is one of the reasons sudden restrictive dieting can affect the cycle.

What might a doctor do?

A doctor will usually start with a conversation about her symptoms and lifestyle, followed by a blood test to check hormone levels. 

If the blood test suggests a specific cause, such as PMOS or a thyroid problem, treatment can begin.

Conditions like PMOS respond well to management, and periods often become more regular once the underlying issue is addressed.

FAQ

My daughter's period was regular for six months, and now it has not come for two months, is that normal?

Two months without a period after having a regular cycle is worth monitoring. If it reaches three months, a doctor visit is a good idea to rule out any underlying cause.

Can PMOS cause a teenager's period to stop?

Yes. PMOS is one of the most common hormonal conditions in teenage girls and can cause irregular or absent periods. 

It is often also associated with acne, weight changes, and unwanted hair growth.

Could over-exercising be behind my daughter's stopped periods?

Intensive training, particularly in endurance sports, gymnastics, or dance, can reduce the hormonal activity needed to maintain periods. 

If exercise levels are high, this is worth discussing with a doctor or sports health professional.

Should I be concerned about eating habits if her period has stopped?

If periods have stopped and you have also noticed changes in her eating habits or weight, it is worth speaking to your doctor. 

Very low calorie intake can suppress ovulation, and in some cases, a stopped period can be one of the first visible signs of a disordered relationship with food.

For more detail on what is normal for teen periods, the luna article on irregular periods in teens is a helpful starting point. 

Rated 4.8

Period tracking & more for teens. Guidance for parents.

Find out more