Assisted Reproductive Technology

IVF Stimulation Protocol Compendium

GnRH Agonist · GnRH Antagonist · Minimal Stimulation — comparative analysis

◈
GnRH Agonist
Long Protocol
Oocyte Yield95%
Pregnancy Rate90%
OHSS Risk70%
Cost85%
Complexity90%
Best for
● Normal responders
● Embryo freezing candidates
◇
GnRH Antagonist
Flexible Protocol
Oocyte Yield72%
Pregnancy Rate65%
OHSS Risk40%
Cost60%
Complexity55%
Best for
● PCOS patients
● High OHSS risk
○
Minimal Stimulation
Mini-IVF Protocol
Oocyte Yield40%
Pregnancy Rate62%
OHSS Risk15%
Cost25%
Complexity30%
Best for
● Poor ovarian reserve
● Budget-conscious patients
At a Glance
Feature GnRH Agonist GnRH Antagonist Minimal Stimulation
Duration4–6 weeks2–3 weeks2–3 weeks
Gonadotropin Use~25 ampoulesModerate~5.7 ampoules
Oocyte YieldHighestModerateLowest
Pregnancy RateBestLowerComparable
OHSS RiskHigherLowerLowest
CostHighestModerateLowest
Embryo FreezingExcellentGoodLimited
◈
GnRH Agonist
Long Protocol
Gold Standard
◇
GnRH Antagonist
Flexible Protocol
Shorter, Safer
○
Minimal Stimulation
Mini-IVF
Gentle & Affordable
Mechanism & Timing

GnRH agonist (e.g., triptorelin) administered from cycle day 21, followed by gonadotropins at 150–225 IU/day from day 2 of the next cycle. Both continue until HCG trigger when follicles reach 16–18 mm (approximately 14 days into the gonadotropin phase).

Duration
4–6 weeks
Gonadotropin Use
~25 ampoules
Advantages
✓Highest oocyte yield of all protocols
✓Best cumulative pregnancy & implantation rates
✓Superior embryo cryopreservation potential
✓Better outcomes in extreme BMI & advanced age
✓Well-established, extensive evidence base
Limitations
✗Longest treatment duration (4–6 weeks)
✗Most gonadotropin ampoules required
✗Risk of ovarian cyst formation
✗Menopausal symptoms (hot flushes, vaginal dryness)
✗Highest cost; higher OHSS risk in PCOS
Drugs Used
Triptorelin Leuprorelin Goserelin Nafarelin FSH / HMG HCG trigger
Ideal Patient Profile
◆Normal responders
◆High responders
◆Patients needing embryo freezing
◆Advanced age patients
Mechanism & Timing

Gonadotropins at 150–225 IU/day started on day 2/3. GnRH antagonist (e.g., cetrorelix) added around day 6 or when follicles reach ≥14 mm, continuing until HCG trigger. Rapid-onset suppression of LH without an initial flare effect.

Duration
2–3 weeks
Gonadotropin Use
Moderate
Advantages
✓Shorter treatment duration
✓Fewer gonadotropin ampoules needed
✓Better OHSS prevention, especially in PCOS
✓Rapid LH suppression without flare
✓More oocytes in prior poor agonist responders
Limitations
✗Lower pregnancy & implantation rates
✗Lower LH impairs estrogen secretion
✗Reduced overall follicular production
✗Risk of congenital anomalies (Beckwith-Wiedemann)
✗Moderate cost
Drugs Used
Cetrorelix Ganirelix FSH / HMG HCG trigger GnRH agonist trigger
Ideal Patient Profile
◆PCOS patients
◆High OHSS risk patients
◆Previous poor agonist responders
◆Patients seeking shorter cycles
Mechanism & Timing

Clomiphene citrate (CC) started around day 6, combined with HMG, continuing to HCG trigger. CC suppresses premature LH surge while maintaining follicular development. Letrozole (2.5 mg from day 2–3 for 5 days) can substitute CC in clomiphene-resistant patients.

Duration
2–3 weeks
Gonadotropin Use
~5.7 ampoules
Advantages
✓Lowest cost of all protocols
✓Fewest ampoules (5.7 vs 25 in agonist)
✓Pregnancy rate comparable to agonist
✓Fewer monitoring visits & ultrasounds
✓Lowest OHSS risk; fewer mitotic errors
Limitations
✗Fewest mature oocytes retrieved
✗Fewer viable embryos for freezing
✗Anti-estrogenic CC effects on endometrium
✗Higher multiple pregnancy risk
✗Letrozole not approved for ovulation induction
✗Congenital anomaly risk with CC
Drugs Used
Clomiphene Citrate HMG / FSH HCG trigger Letrozole (alt.)
Ideal Patient Profile
◆Poor ovarian reserve
◆Poor responders
◆Older patients (>40 years)
◆Budget-conscious patients
Protocol A
⇄
Protocol B
Select Patient Profile
⚠ This tool is for educational reference only. Protocol selection must be individualized by a qualified reproductive endocrinologist based on full clinical assessment including ovarian reserve, age, BMI, prior IVF history, PCOS status, and patient preferences.