Clinical Implications of Minipuberty

Hormone levels at 1–3 months of life predict adult reproductive capacity and can flag hypogonadism before symptoms appear

Journal: The New England Journal of Medicine | Published: 2026-03-26 | Type: Review | PMID: 41880614 Authors: Anders Juul (Department of Growth and Reproduction, Copenhagen University Hospital-Rigshospitalet, Copenhagen) Funding/COI: Not listed

Summary

Minipuberty is a brief, intense activation of the hypothalamic-pituitary-gonadal (HPG) axis in the first months of life — before the axis goes dormant for roughly a decade. In boys aged 1–3 months, testosterone and Sertoli cell hormone levels rival adult values. This NEJM review argues the window is clinically underutilized: it is the best early opportunity to identify congenital hypogonadotropic hypogonadism (CHH) and other reproductive disorders, and the hormone levels reached during this period appear to predict adult fertility.

Claims

• In boys aged 1–3 months, FSH and LH surge, driving testicular Leydig cells to produce testosterone and insulin-like 3 (INSL3), and Sertoli cells to produce inhibin B and antimüllerian hormone (AMH)
• Infant girls also reach adult-equivalent FSH and LH concentrations during this window
• Following minipuberty, the HPG axis is suppressed for approximately 10 years until the onset of puberty
• Minipuberty hormone profiles can identify congenital hypogonadotropic hypogonadism — a rare but treatable cause of infertility — before clinical features become apparent
• The review asserts that hormone levels during minipuberty predict adult reproductive capacity
• Minipuberty data can inform dosing of gonadotropin replacement therapy in affected infants

Study Quality

This is a narrative review by a single author — not a systematic review or meta-analysis. It does not include pooled effect sizes, heterogeneity statistics, or a pre-registered literature synthesis. The quality of the underlying evidence it draws on varies and is not formally graded. The review represents one researcher's synthesis of the field, not a reproducible, protocol-driven analysis.

That said, NEJM peer review is rigorous, and Juul's group at Rigshospitalet has an extensive publication record on HPG axis development in infants. The diagnostic framing — using minipuberty as an early window to detect CHH — is grounded in plausible physiology and is consistent with existing cohort literature on pediatric endocrinology.

Red Flags

• Single-author narrative review: literature selection bias is possible and unverifiable without seeing the full paper
• Funding and conflicts of interest are not disclosed in available metadata; Juul's lab is highly active in this exact space
• The claim that minipuberty "predicts adult reproductive capacity" is stated without quantified effect sizes in the abstract — the magnitude and reliability of this predictive relationship is unclear
• No primary data are presented; this review synthesizes existing literature rather than generating new findings
• Clinical utility of gonadotropin dosing guidance derived from minipuberty levels requires validation in interventional trials; none are mentioned in the abstract

Strengths

• Published in the NEJM, signaling high editorial and peer-review scrutiny
• Addresses a diagnostically underappreciated developmental window with real clinical consequences
• Covers HPG axis development in both males and females, not narrowly focused on male outcomes
• Clinically actionable framing around CHH — a treatable condition where early diagnosis matters
• Scope is tightly defined: a specific physiological window, a specific hormone axis, specific downstream diagnoses

Verdict

This is a synthesis, not new data — but it is an NEJM synthesis by a researcher with deep domain expertise, which carries more weight than a typical narrative review. The core argument that the postnatal 1–3 month hormone surge is a diagnostically underused window for identifying hypogonadotropic hypogonadism is physiologically coherent and clinically relevant for pediatric urologists and endocrinologists. The prediction that minipuberty levels forecast adult fertility is the boldest claim here, and also the one most in need of quantified primary data before it changes clinical practice. Read the full paper for the CHH diagnostic framing; treat the adult fertility prediction claim with appropriate skepticism until effect sizes are in hand.