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Understanding Menstrual Cycles After First Period

This observational study aims to understand how girls' menstrual cycles develop and become regular in the two years after their first period (menarche). Researchers are particularly interested in girls who may have a higher chance of developing Polycystic Ovary Syndrome (PCOS), a condition that can cause irregular periods. The study will help identify what a healthy progression of puberty looks like and how to spot early signs of hormone problems. There are no interventions or medications being tested. Success for this study means determining how long it takes for girls to have two regular, ovulatory cycles in a row. The study plans to enroll 400 participants.

Study design
This is an observational study involving up to 400 female participants. It is not testing any specific interventions or drugs.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
The primary endpoint is measured during the first two post-menarcheal years.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT03986021

Reproductive Axis Maturation in the Early Post-Menarchal Years

Recruiting
Not specifiedAges 8–65Observational
National Institute of Environmental Health Sciences (NIEHS)
~400 participants
Updated 2026-09-08 on ClinicalTrials.gov

At a glance

Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
To determine the time from menarche to regular ovulatory cycles, defined as two consecutive ovulatory cycles in girls of variable genetic risk for PCOS
Measured over Defined as two consecutive ovulatory cycles with normal (10-14 day) luteal phase length during the first two post-menarchal years

Conditions

Reproductive Physiological Processes
Pediatrics
Adolescent Health
Adolescent Development

Explore related trials

Polycystic Ovary SyndromePubertyParathyroid HormoneProlactinTestosterone

NCT03986021

Where you'd take part

This study runs at 1 site. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • NIEHS Clinical Research Unit (CRU)

    Research Triangle Park, North Carolinastudy coordinator listed

    Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Study leadership

  • Natalie D Shaw, M.D. · PRINCIPAL_INVESTIGATOR · National Institute of Environmental Health Sciences (NIEHS)

Who to contact

NIEHS Join A Study Recruitment Group
[email protected]
(855) 696-4347
Email the study team

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Eligibility criteria

Inclusion

Age 8-14.5 years old
Healthy weight, defined as having a body weight \>85% of expected (EBW) and a body mass index (BMI) \<99th percentile
Some breast development
Pre-menarche
Age at menarche 10-14.5 years old
Healthy weight, defined as having a body weight \>85% of expected (EBW) and a body mass index (BMI) \<99th percentile
Approximately \< 6 months post-menarchal (will typically have completed 4 or fewer menstrual cycles)
Biochemical criteria: normal thyroid hormone, prolactin, and testosterone levels
Age at menarche 10-14.5 years old
Healthy weight, defined as having a body weight \>85% of expected (EBW) and a body mass index (BMI) \<99th percentile
Within 1 year of menarche
Biochemical criteria: normal thyroid hormone, prolactin, and testosterone levels
Age 11-17.5 years old
Approximately 2-5 years post-menarchal
Biochemical criteria: normal thyroid hormone and prolactin
Age \>=18-34 years old
PCOS diagnosis
at least 3-years post-menarchal with irregular menstrual cycles
Biochemical (blood) or clinical signs of high androgen levels
Age \>=18-34 years old
at least 3-years post-menarchal with regular menstrual cycles every 21-35 days
Age \>=18-65 years old
Biological mother of A Girl's First Period participant

Exclusion

Taking or planning to take medications that affect reproductive hormones in the next 2 to 3 years (e.g. birth control pills, biotin supplements).
Planning to move more than 60 miles from the CRU within the next 2 to 3 years
Chronic medical condition, including but not limited to diabetes mellitus, congenital adrenal hyperplasia, cystic fibrosis, sickle cell disease, inflammatory bowel disease, juvenile rheumatoid arthritis, and lupus.
First-degree relative with polycystic ovarian syndrome, premature ovarian insufficiency, hypogonadotropic hypogonadism, or other pubertal development disorder
Excessive exercise (defined as running \>20 miles per week or its equivalent)
Pregnancy
Taking or planning to take medications that affect reproductive hormones in the next 2 to 3 years (e.g. birth control pills, biotin supplements).
Planning to move more than 60 miles from the CRU within the next 2 to 3 years
Chronic medical condition, including but not limited to diabetes mellitus, congenital adrenal hyperplasia, cystic fibrosis, sickle cell disease, inflammatory bowel disease, juvenile rheumatoid arthritis, and lupus.
First-degree relative with polycystic ovarian syndrome, premature ovarian insufficiency, hypogonadotropic hypogonadism, or other pubertal development disorder
Excessive exercise (defined as running \>20 miles per week or its equivalent)
Anemia (defined as hemoglobin \<12.0 g/dl)
Participants with hemoglobin between 11.5 g/dl and 12.0 g/dl may still participate by providing dried blood spots, or no more than 18 ml of blood during any given interval.
Pregnancy
Taking or planning to take medications that affect reproductive hormones in the next 1-2 years (e.g. birth control pills, biotin supplements).
Planning to move more than 60 miles from the CRU within the next year
Chronic medical condition, including but not limited to diabetes mellitus, congenital adrenal hyperplasia, cystic fibrosis, sickle cell disease, inflammatory bowel disease, juvenile rheumatoid arthritis, and lupus.
First-degree relative with polycystic ovarian syndrome, premature ovarian insufficiency, hypogonadotropic hypogonadism, or other pubertal development disorder
Excessive exercise (defined as running \>20 miles per week or its equivalent)
Anemia (defined as hemoglobin \<12.0 g/dl)
Participants with hemoglobin between 11.5 g/dl and 12.0 g/dl may still participate by providing dried blood spots, or no more than 18 ml of blood during any given interval.
Pregnancy
Taking or planning to take medications that affect reproductive hormones in the next 2 to 3 years (e.g. birth control pills, biotin supplements).
Planning to move more than 60 miles from the CRU within the next 6 months
Chronic medical condition, including but not limited to diabetes mellitus, congenital adrenal hyperplasia, cystic fibrosis, sickle cell disease, inflammatory bowel disease, juvenile rheumatoid arthritis, and lupus.
Anemia (defined as hemoglobin \<12.0 g/dl)
Participants with hemoglobin between 11.5 g/dl and 12.0 g/dl may still participate by providing dried blood spots, or no more than 18 ml of blood during any given interval.
Pregnancy
Cannot be taking any medications that affect reproductive or metabolic hormones (e.g. birth control pill, biotin supplements, spironolactone, metformin).
Chronic medical condition, including but not limited to diabetes mellitus, congenital adrenal hyperplasia, cystic fibrosis, sickle cell disease, inflammatory bowel disease, juvenile rheumatoid arthritis, and lupus.
Pregnancy
Cannot be taking any medications that affect reproductive or metabolic hormones (e.g. birth control pill, biotin supplements, spironolactone, metformin).
Chronic medical condition, including but not limited to diabetes mellitus, congenital adrenal hyperplasia, cystic fibrosis, sickle cell disease, inflammatory bowel disease, juvenile rheumatoid arthritis, and lupus.
PCOS diagnosis or first-degree relative with disorder
Pregnancy
Chronic medical condition, including but not limited to diabetes mellitus, congenital adrenal hyperplasia, cystic fibrosis, sickle cell disease, inflammatory bowel disease, juvenile rheumatoid arthritis, and lupus.
Pregnancy

What this trial measures

  • To determine the time from menarche to regular ovulatory cycles, defined as two consecutive ovulatory cycles in girls of variable genetic risk for PCOSDefined as two consecutive ovulatory cycles with normal (10-14 day) luteal phase length during the first two post-menarchal years

    We hypothesize that the temporal sequence of reproductive maturation will consist of anovulatory cycles (representing a time of unopposed estrogen exposure), ovulatory cycles with a short luteal phase (estrogen with low progesterone exposure), and finally, ovulatory cycles with a normal luteal phase length (estrogen action fully counterbalanced by progesterone action)