Ovulation Induction Protocol
For women with PCOS and anovulatory infertility, start with lifestyle modifications for 3-6 months, then use letrozole as first-line pharmacological therapy, followed by low-dose FSH gonadotropins (starting at 37.5-50 IU/day) as second-line treatment if letrozole fails. 1
First-Line Approach: Lifestyle Modifications
Begin with lifestyle interventions for 3-6 months in all women with PCOS-related anovulation 1. Target 5-10% weight loss through:
- Calorie restriction (500-700 kcal/day deficit)
- 150 minutes/week of moderate-high intensity aerobic exercise
- Behavioral interventions
Critical caveat: Pharmacological ovulation induction is contraindicated in women with BMI >35 kg/m² until weight optimization occurs 1.
Second-Line: Pharmacological Ovulation Induction
Letrozole (Preferred First-Line Medication)
Three major clinical practice guidelines now recommend letrozole as the primary pharmacological agent 1, representing a significant shift from older recommendations that favored clomiphene citrate. This change reflects superior live birth outcomes with letrozole in PCOS patients.
Clomiphene Citrate (Alternative)
While historically first-line, clomiphene citrate remains acceptable when letrozole is unavailable 2. Patients must be counseled about increased multiple pregnancy risk.
Third-Line: Gonadotropin Therapy
For women who fail to ovulate or conceive with letrozole/clomiphene:
Low-Dose Step-Up FSH Protocol 1
- Starting dose: 37.5-50 IU/day FSH
- Duration: Up to 14 days of stimulation
- Monitoring: Close ultrasound and hormonal surveillance required
- Maximum cycles: 6 stimulation cycles
- Goal: Monofollicular development to minimize multiple pregnancy risk
Recent evidence confirms safety and efficacy: A 2025 Cochrane review found gonadotropins (FSH) result in significantly more live births than continued clomiphene citrate (RR 1.24,95% CI 1.05-1.46) without increasing multiple pregnancies 3. When properly monitored, gonadotropins show cumulative live birth rates of 18.2%, 34.5%, and 41.1% after 1,2, and 3 cycles respectively, with only 2% multiple pregnancy rate and zero OHSS cases 4.
Type of Gonadotropin
There is little difference between recombinant FSH (rFSH) and urinary-derived gonadotropins in terms of live birth, clinical pregnancy, or multiple pregnancy rates 3. Providers can select based on availability and cost.
Fourth-Line: Laparoscopic Ovarian Drilling
Consider when clomiphene-resistant PCOS exists, particularly if other laparoscopic indications are present 2. This avoids ongoing medication costs and multiple pregnancy risks but carries surgical risks.
Fifth-Line: IVF
Reserve for women who fail gonadotropin therapy or have additional infertility factors 1, 2. Use GnRH antagonist protocols with metformin to reduce OHSS risk 1.
Critical Monitoring Requirements
When using gonadotropins:
- Mandatory ultrasound monitoring of follicular development
- Hormonal surveillance
- Cycle cancellation if excessive follicular response occurs (10.5% cancellation rate is acceptable) 4
- Single insemination per cycle is sufficient 5
Timing Considerations
- With HCG trigger: Perform single IUI 24-40 hours post-injection 5
- Natural cycles: Perform IUI 1 day after LH rise 5
Adjunctive Metformin
Metformin combined with clomiphene may increase ovulation rates but does not significantly improve live birth rates over clomiphene alone 2. Consider adding metformin in clomiphene-resistant women who are older with visceral obesity 2. Stop metformin once pregnancy is confirmed 1.
Age and BMI Considerations
Prognosis is significantly reduced in women >35 years (23.8% vs 55.3% pregnancy rate, P=0.006) and BMI >25 kg/m² (40.6% vs 56.7%, P=0.027) 4. Counsel these patients about lower success rates and consider earlier escalation to advanced therapies.