International Day of the Girl: how the endometriosis innovation gap affects girls’ health and opportunities

By Dr Cécile Ventola 6 October 2026

5 min read

Sexual & Reproductive HealthEndometriosisDiagnosticsDrugs

Introduction

Every year, the International Day of the Girl draws attention to the barriers that prevent girls from living healthy lives and reaching their full potential. One of those barriers may begin with something seemingly ordinary: their first periods.

Endometriosis is commonly discussed as a women’s health condition. But for many of those affected, symptoms do not begin in adulthood. Pelvic pain and severe dysmenorrhoea can start in adolescence, sometimes from around menarche. Yet girls experiencing these symptoms are affected even more strongly by the innovation gap for endometriosis, as many of the tools available to recognise, diagnose and treat the disease are poorly suited to them.

The diagnostic path: age-related dismissal and inadequate tools

While long delays in diagnosing endometriosis are well documented for adults, studies of diagnostic delay in adolescents have identified specific normalisation of symptoms by both patients and healthcare providers. New onset of pain symptoms in adulthood might be considered a stronger clinical sign than menarche pain.¹ A 2017 study showed that the average 7 years a woman waits before getting an endometriosis diagnosis extend to 12 years when the onset was in adolescence.² And even when endometriosis is suspected, the already limited toolbox appears even more constrained for girls. While clinical guidance is moving away from invasive laparoscopic surgery, some standard gynaecological examinations, such as transvaginal ultrasound, may also be inappropriate for adolescents. In the absence of established biomarker tests, imaging has limitations, especially for superficial endometriosis, which is more likely in adolescents.³ The need for a simple, accurate, non-invasive test for endometriosis thus appears particularly urgent for girls suffering from the disease to limit diagnostic delays. The recent integration of EndoSure and Endotest into the care options available through the NHS is an encouraging development, although additional evidence of effectiveness is still needed before these tools can be permanently implemented in routine care.⁴

Treatment options are even narrower for girls

The challenge does not end with diagnosis. There is no cure for endometriosis and most treatments available are repurposed medicines targeting symptom management. Hormonal contraceptives and progestogens are recommended as first-line hormonal treatments for adolescents with severe dysmenorrhoea or suspected endometriosis. But much of the evidence underpinning medical treatment for endometriosis has historically been generated in adults, leaving a thinner evidence base for adolescent patients. The 2022 ESHRE guidelines explicitly note the scarcity of high-quality adolescent-specific treatment evidence.⁵

Some treatment considerations are also particularly important during adolescence. GnRH agonists, a hormonal treatment lowering estrogen production routinely used to improve endometriosis symptoms, can for example affect bone mineral density — a significant concern during the years in which adolescents are still accumulating peak bone mass. They can be used in selected adolescents when first-line hormonal treatments, such as hormonal contraceptives, have failed, but guidelines recommend careful consideration of potential long-term risks and the use of add-back therapy, like progestin, to minimize side-effects.

This highlights a broader problem. Girls do not simply need access to the treatments developed for adult women. They need treatments demonstrated to be safe and effective during a distinct and important stage of physical development — potentially for a disease they may live with for decades.

How the innovation gap affects the present and future of adolescent girls

The International Day of the Girl is an opportunity to ask not only whether girls have access to healthcare, but whether health innovation itself accounts for their needs.

Our pipeline data shows how far endometriosis innovation still has to go. Our 2025 Flying Blind report highlighted the urgent need for accurate, accessible and non-invasive diagnostics and treatments that go beyond symptom suppression and can be safely used over the long term. The existing endometriosis innovation gap may be even more consequential for girls because both diagnosis and treatment are constrained by age.

Diagnostic delays and lack of treatment can have lasting effects when they occur during formative years: a disease beginning with menstruation can quietly interfere with girls' education at precisely the point at which they are establishing independence and educational trajectories. Reviews specifically identify increased school absenteeism and major effects on physical, emotional and social wellbeing.⁶

The specificity of endometriosis as a paediatric disease reflects the broader issue with recognizing women’s pain and investing in underdeveloped biomedical innovation. Closing the endometriosis innovation gap is therefore not only about improving women’s health in adulthood, but also about giving girls the tools they need to participate fully in education, relationships and everyday life from the beginning of their reproductive years.

A girl missing school every month because of her period should not have to wait until adulthood for her pain to be taken seriously. Endometriosis does not wait for adulthood. Neither should innovation.