What Does a Reproductive Endocrinologist Do? A Guide to REI Care
Navigating infertility or family-building challenges can feel overwhelming, particularly when deciding which specialist to consult. A reproductive endocrinologist (REI) is a physician uniquely trained to evaluate and treat the full spectrum of reproductive health concerns, offering a level of subspecialty expertise that extends well beyond general gynecology or urology.
Training and Clinical Background
Reproductive endocrinologists complete four years of obstetrics and gynecology residency before pursuing an additional two to three years of fellowship training in reproductive endocrinology and infertility. Some REIs enter the field through urology, particularly those who focus on male factor infertility. This layered training equips them to assess both hormonal and structural contributors to reproductive challenges, giving them a comprehensive view of the conditions that affect conception.
Areas of Specialization
REIs diagnose and manage a broad range of conditions, including ovulatory disorders, Polyendocrine Metabolic Ovarian Syndrome (PMOS), endometriosis, uterine anomalies, diminished ovarian reserve, and male factor infertility. They are also central to fertility preservation for patients facing cancer treatment — a discipline known as oncofertility — as well as family building for LGBTQ+ individuals and couples who require donor gametes, gestational carriers, or other assisted reproductive technologies. Among the treatments REIs perform, in vitro fertilization (IVF) is one of the most well-known and involves retrieving eggs, fertilizing them in a laboratory, and transferring resulting embryos into the uterus.
When to See a Reproductive Endocrinologist
Patients are generally advised to consult an REI after six months to one year of unsuccessful conception attempts, depending on age and individual health factors. However, earlier evaluation is appropriate in certain circumstances — including a known diagnosis such as PMOS or endometriosis, a history of recurrent pregnancy loss, or a prior cancer diagnosis requiring urgent fertility preservation. LGBTQ+ individuals and those pursuing single parenthood are also encouraged to connect with an REI at the outset of their family-building planning, as a consultation can help clarify which pathways and timelines best align with their goals.
Beginning care with a specialist who understands the full complexity of reproductive medicine can make a meaningful difference in the quality and clarity of that journey. To learn more about how the REI team at NYU Langone Fertility Center can support your goals, schedule a consultation today.
Categories
The NYU Langone Fertility Center Blog
At NYU Langone Fertility Center, our first job is to support our patients as they become educated about their reproductive health and fertility treatment options. Our blog connects patients with the most up-to-date information, technologies, and insights into fertility care. From egg freezing to IVF to third-party reproduction options, we explore every facet of assisted reproductive technology and empower patients with the knowledge they need to navigate their family building journeys.