Periods & cycle

No First Period by 15: When to Ask

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Most girls have a first period by age 15. If your daughter hasn't — or has had no breast development by 13 — an evaluation is reasonable rather than a wait-and-see [1]. Common causes are benign, including late maturing, low body weight, thyroid problems, and PCOS [2][5].

Last updated: July 2026

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When is a missing first period worth evaluating?

A first period is expected by certain developmental markers, and passing them is the signal to ask. According to ACOG, which treats the menstrual cycle as a vital sign, evaluation is reasonable when a girl has had no period by age 15, or no period within 3 years of breast development starting, or no breast development at all by age 13 1.

These markers matter because most girls menstruate within about 2 to 3 years of puberty's first signs. Reaching one of these points does not mean something is wrong — it means the timing has crossed from ordinary variation into the range where a look is worthwhile 1.

What are the common reasons a period is late to arrive?

Most causes of a delayed first period are benign and fall into a few groups. The Office on Women's Health and specialty guidelines describe the usual explanations 32:

  • Constitutional delay, a normal and often familial pattern of later maturing that catches up on its own
  • Low energy availability from intense sports, restrictive eating, or significant weight loss, which can pause the hormonal signals that start periods
  • Thyroid or other hormone conditions that are treatable once identified
  • Polycystic ovary syndrome, which can delay or disrupt early cycles
  • Less commonly, a difference in reproductive anatomy or in how the ovaries develop

A clinician sorts these apart with a history, an exam, and a few tests. Our guide to delayed puberty in a child covers the broader picture.

Could disordered eating or sports be the cause?

Low energy availability is one of the most common and most overlooked reasons periods are late or absent in teens. When the body takes in less fuel than it burns — through intense training, restrictive eating, or rapid weight loss — it can switch off the hormonal signals that drive periods, a pattern the Endocrine Society calls functional hypothalamic amenorrhea 2.

This is the body protecting itself, and periods usually return once energy balance and weight are restored 2. Because this cause can point to disordered eating, it is worth gentle attention rather than pressure. Our guide to eating disorder warning signs in teenagers can help you recognize the signs.

What happens at the first appointment?

A first evaluation for a delayed period is usually low-key and non-invasive. A clinician typically starts with a growth and puberty history, a general physical exam, and questions about diet, exercise, and family timing — often when the mother and sisters started 3.

Simple blood tests can check thyroid, prolactin, and reproductive hormones, and an ultrasound is sometimes added to look at anatomy. A pelvic exam is usually not needed at this stage. Depending on results, some teens are simply monitored while nature catches up, while others are found to have a specific, treatable cause such as primary ovarian insufficiency or PCOS 45.

When a delayed first period needs a pediatrician

A clinician can tell reassuring late maturing from a cause that benefits from early treatment. A pediatrician, adolescent-medicine clinician, or gynecologist can carry out the evaluation, explain what is normal, and involve your daughter in a way that feels supportive rather than clinical 1.

Starting the conversation by age 15 — or sooner if she has had no signs of puberty by 13 — means any treatable cause is caught early 1. Our guides to signs of early puberty in a child and how to talk to your child about puberty can help at home. Gale can help you prepare for that first visit.

Common questions

It can be, but 15 is the age at which most guidelines suggest an evaluation rather than continued waiting. Many girls who start late are simply maturing on a later, often familial schedule. A check helps confirm that and rules out treatable causes.

That is actually the more important flag. No breast development by age 13 is a reason to check sooner, since puberty normally begins before periods do. If she has been developing normally and just hasn't started her period, the situation is usually less urgent, though still worth a visit by 15.

Yes. Intense training combined with not eating enough to match the effort can pause or delay periods. This is common in sports like gymnastics, dance, and distance running. It is worth attention because it can affect bone health and sometimes signals disordered eating.

Often not, especially with common causes like constitutional delay. Some specific conditions found during evaluation can affect fertility, which is one reason checking early is helpful — it allows any underlying cause to be understood and managed in good time.

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When a delayed first period needs a closer look

  • —No first period by age 15, or no breast development by age 13, is a reason to seek clinician review.
  • —Skipping meals, intense exercise, or rapid weight loss alongside no periods can signal disordered eating and is a reason to seek clinician review; the National Alliance for Eating Disorders helpline (1-866-662-1235) offers support.
  • —Cyclic pelvic pain without any bleeding is a reason to seek clinician review, as it can point to a blockage in the reproductive tract.
  • —Signs of puberty that started years ago but never led to a period is a reason to seek clinician review.

This article is general health education, not medical advice. Whether your daughter's delayed period needs evaluation is a decision for her pediatrician, adolescent-medicine clinician, or gynecologist, based on her full growth and health history.

References

  1. 1.American College of Obstetricians and Gynecologists (2015). ACOG Committee Opinion No. 651: Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign. Obstetrics & Gynecology. doi:10.1097/AOG.0000000000001215 ✓ACOG committee opinion establishing the evaluation thresholds for delayed menarche: no period by age 15, no period within 3 years of thelarche, or no breast development by age 13.
  2. 2.Gordon CM, et al. (Endocrine Society) (2017). Functional Hypothalamic Amenorrhea: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. doi:10.1210/jc.2017-00131 ✓Endocrine Society guideline describing functional hypothalamic amenorrhea from low energy availability (intense exercise, restrictive eating, weight loss) as a cause of absent periods that typically resolves with restored energy balance.
  3. 3.Office on Women's Health (U.S. HHS) (2025). Period problems. Office on Women's Health (womenshealth.gov), U.S. HHS. link ✓Patient-facing overview of common causes of absent or delayed periods and what a first evaluation involves.
  4. 4.Webber L, et al. (ESHRE) (2016). ESHRE Guideline: management of women with premature ovarian insufficiency. Human Reproduction. doi:10.1093/humrep/dew027 ✓ESHRE guideline on premature ovarian insufficiency, a treatable cause that can present as a delayed or absent first period.
  5. 5.Teede HJ, Tay CT, Laven J, et al. (International PCOS guideline consortium) (2023). Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Journal of Clinical Endocrinology & Metabolism. doi:10.1210/clinem/dgad463 ✓International PCOS guideline noting that PCOS can delay or disrupt early cycles and present in adolescence as irregular or absent periods.

5 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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