Fertility and IVF — Find Specialists & Top Hospitals Worldwide | MyMedicPlus

Reproductive Endocrinology and Infertility (REI) is a recognised subspecialty of obstetrics and gynaecology focused on the hormonal causes of infertility and the clinical application of assisted reproductive technologies (ART) to help individuals and couples achieve pregnancy. REI specialists — often referred to as fertility specialists — are uniquely trained to diagnose and treat the full spectrum of male and female reproductive failure using a combination of medical, surgical, and laboratory-based approaches.

The field occupies a distinct niche from general gynaecology. While gynaecologists manage menstrual and pelvic disorders and provide obstetric care, reproductive endocrinologists focus specifically on the physiology of conception, the diagnosis of infertility, and the design and implementation of treatment protocols that may include ovulation induction, intrauterine insemination (IUI), or in vitro fertilisation (IVF) with advanced laboratory techniques. REI specialists also manage fertility preservation for patients who need chemotherapy or radiation before cancer treatment, and they counsel and treat patients with premature ovarian insufficiency and recurrent pregnancy loss.

The specialty involves close collaboration with embryologists, andrologists (who specialise in the male reproductive system and sperm analysis), reproductive geneticists (for preimplantation genetic testing), and psychologists who support patients through the emotional challenges of infertility diagnosis and treatment. IVF success rates have improved significantly over two decades due to improvements in embryo culture systems, cryopreservation techniques, embryo selection, and endometrial receptivity assessment, making this one of the most rapidly advancing subspecialties in medicine.

Fertility specialists diagnose and treat causes of infertility and recurrent pregnancy loss in both partners:

• Ovulatory disorders (WHO Group I–III): Failure to ovulate regularly, including WHO Group I (hypothalamic anovulation, such as functional hypothalamic amenorrhoea), Group II (polycystic ovary syndrome, the most common cause of anovulatory infertility), and Group III (premature ovarian insufficiency).
• Polycystic ovary syndrome (PCOS): Complex endocrine disorder causing irregular periods, elevated androgens, polycystic ovaries, and insulin resistance; the most common hormonal cause of female infertility worldwide.
• Endometriosis: Presence of endometrial-like tissue outside the uterus causing pelvic adhesions, tubal obstruction, ovarian endometriomas, and impaired embryo implantation; affects up to 10% of women of reproductive age.
• Tubal factor infertility: Blocked, damaged, or absent fallopian tubes due to prior pelvic inflammatory disease, chlamydia infection, previous tubal ligation, or prior ectopic pregnancy.
• Male factor infertility: Low sperm count (oligozoospermia), absent sperm (azoospermia), poor sperm motility (asthenozoospermia), or abnormal sperm morphology (teratozoospermia); accounts for approximately 40–50% of infertility cases.
• Unexplained infertility: Failure to conceive after 12 months of regular unprotected intercourse with normal semen analysis, ovulatory function, and tubal patency on testing in approximately 25–30% of infertile couples.
• Recurrent pregnancy loss (RPL): Two or more clinical pregnancy losses; evaluation for uterine anomalies (septum, fibroids, polyps), antiphospholipid syndrome, thrombophilias, chromosomal abnormalities, and thyroid dysfunction.
• Premature ovarian insufficiency (POI): Loss of normal ovarian function before age 40 causing amenorrhoea, oestrogen deficiency, and infertility; requires egg donation for pregnancy in most cases.
• Uterine factor infertility: Congenital anomalies (bicornuate, unicornuate, or septate uterus), intrauterine adhesions (Asherman syndrome), submucosal fibroids, or endometrial polyps that impair implantation.
• Fertility preservation: Fertility-threatening diagnoses (cancer, autoimmune disease requiring gonadotoxic therapy) may prompt emergency egg freezing, embryo freezing, or ovarian tissue cryopreservation before treatment begins.

Fertility specialists employ a progression of assisted reproductive technologies based on diagnosis and treatment response:

• Ovulation induction with timed intercourse: Administration of clomiphene citrate or letrozole to stimulate follicle development in anovulatory patients; combined with ultrasound monitoring and timed intercourse or IUI.
• Intrauterine insemination (IUI): Preparation and concentration of a semen sample, then placing the washed sperm directly into the uterine cavity at the time of ovulation. Simpler, less expensive, and less invasive than IVF; appropriate for mild male factor, cervical factor, or unexplained infertility with good ovarian reserve.
• In vitro fertilisation (IVF): The cornerstone of ART. Controlled ovarian stimulation with gonadotrophins stimulates multiple follicle development; eggs are retrieved under ultrasound guidance with sedation; fertilisation occurs in the laboratory; resulting embryos are cultured and transferred to the uterus at the blastocyst stage (day 5–6).
• Intracytoplasmic sperm injection (ICSI): A single sperm is injected directly into an egg under microscopy. Indicated for severe male factor infertility, low fertilisation rates in prior IVF cycles, and use of surgically retrieved sperm.
• Preimplantation genetic testing (PGT): Biopsy of blastocyst trophectoderm cells for chromosomal analysis (PGT-A, for aneuploidy screening) or specific gene mutation testing (PGT-M, for monogenic diseases such as cystic fibrosis, BRCA mutations). Used to select chromosomally normal embryos for transfer.
• Egg and embryo cryopreservation: Vitrification (ultra-rapid freezing) of mature oocytes or embryos for future use; essential for fertility preservation and allows elective frozen embryo transfer cycles.
• Surgical sperm retrieval: When azoospermia is present, sperm may be retrieved surgically by percutaneous epididymal sperm aspiration (PESA), testicular sperm aspiration (TESA), or micro-TESE (microsurgical testicular sperm extraction) for use in ICSI.
• Hysteroscopy and laparoscopy for uterine and pelvic factor: Diagnostic and operative hysteroscopy to identify and treat intrauterine pathology (polyps, septum, adhesions); laparoscopy to diagnose and treat endometriosis, remove ovarian endometriomas, and assess tubal anatomy.

Clinical guidelines provide evidence-based age-stratified thresholds for fertility specialist referral, recognising that female fertility declines significantly with age, particularly after 35.

Standard referral criteria by age: Women under 35 who have not conceived after 12 months of regular (every 2–3 days) unprotected sexual intercourse with no known cause should be evaluated. Women aged 35–39 should be referred after 6 months of unsuccessful trying. Women 40 years or older should seek fertility evaluation immediately without waiting, as ovarian reserve declines rapidly and treatment response diminishes with age.

Earlier referral is always indicated when there is a known fertility-affecting condition: irregular or absent periods suggesting ovulatory dysfunction; a prior diagnosis of PCOS, endometriosis, or pelvic inflammatory disease; known tubal damage from prior infection or surgery; male partner with known or suspected fertility problems (prior testicular surgery, chemotherapy, abnormal prior semen analysis); a history of two or more miscarriages; or a diagnosis that may require gonadotoxic treatment (chemotherapy, pelvic radiotherapy) where fertility preservation is time-sensitive.

Both partners should be evaluated simultaneously at the first fertility appointment — a semen analysis for the male partner and baseline ovarian reserve testing (AFC by ultrasound, AMH level) and a tubal patency assessment (hysterosalpingography or sonohysterography) for the female partner are typically performed early in the work-up to guide treatment decisions efficiently.

Becoming a reproductive endocrinologist and infertility specialist requires one of the longest training pathways in medicine. After completing a 4-year medical degree (MD or DO), candidates undertake a 4-year residency in obstetrics and gynaecology, which provides broad clinical experience across general gynaecology, obstetrics, gynaecologic oncology, and urogynaecology. Passing the ABOG written board examination is required at the end of residency.

Following OB/GYN residency, candidates complete a 3-year fellowship in Reproductive Endocrinology and Infertility (REI). The REI fellowship provides intensive training in reproductive physiology, laboratory embryology, ovarian stimulation protocols, IVF techniques, recurrent pregnancy loss evaluation, fertility preservation, reproductive surgery (hysteroscopy and laparoscopy), and reproductive genetics. Fellows typically perform hundreds of supervised egg retrievals, embryo transfers, and operative hysteroscopy procedures during training.

Board certification in REI is granted by the American Board of Obstetrics and Gynecology (ABOG) upon successful completion of a written qualifying examination and an oral certifying examination assessing clinical case management. Most REI fellows also have the opportunity to pursue research during their 3-year fellowship, contributing to the evidence base for new ART technologies.

In the UK, REI training is embedded within the specialty training programme for Obstetrics and Gynaecology, with subspecialty accreditation through the Reproductive Medicine Subspecialty Training Programme (RCOG), leading to specialist recognition in reproductive medicine. IVF clinics in the UK are regulated by the Human Fertilisation and Embryology Authority (HFEA).

Begin by asking your gynaecologist or primary care physician for a referral to a board-certified reproductive endocrinologist. When evaluating fertility clinics, the most important metric is the live birth rate per IVF cycle (not just the pregnancy or clinical pregnancy rate), stratified by your age group — this is the most clinically meaningful outcome. In the USA, all IVF clinics are required to report annual outcome data to the CDC via the National ART Surveillance System (NASS), published through SART (Society for Assisted Reproductive Technology). In the UK, the Human Fertilisation and Embryology Authority (HFEA) publishes success rates by clinic on their public-facing website.

For your first consultation, both partners should attend. Bring any prior investigations — semen analyses, pelvic ultrasound reports, hysterosalpingography (HSG) results, prior hormone blood tests — and a thorough gynaecological and sexual history. Expect baseline blood tests for ovarian reserve (AMH, day 3 FSH/LH/oestradiol), a transvaginal ultrasound to count antral follicles, and a semen analysis to be organised within the first 1–2 visits.

Consider the clinic's support services, including psychological counselling, because the emotional toll of infertility treatment is significant and often underestimated. Fertility treatment abroad (particularly in destinations such as Greece, Spain, Czech Republic, and India) may offer lower costs, particularly for egg donation or complex protocols, but patients should carefully research clinic credentials, regulatory oversight, and aftercare arrangements before travelling.