What is Ovulation Induction?
💡 Ovulation induction (OI) = fertility drugs to trigger egg development and release. First-line drug: letrozole (2.5–7.5mg, Days 3–7) — preferred for PCOS. Second-line: FSH injections (50–75 IU). Monitored by TVS; trigger shot when follicle ≥18mm. Success: 20–25% per cycle with IUI. Key risk: multiple pregnancy if >2 follicles develop.
Ovulation induction (OI) is the use of fertility medications to stimulate the ovaries to develop and release one or more mature eggs. It is used to treat anovulation (absence of ovulation) — the most common cause of female infertility — and to optimise egg timing for IUI. OI differs from IVF stimulation in intent: the goal is 1–2 follicles, not maximal egg harvest.
🇮🇳 India Context: Ovulation Induction is widely assessed and treated across major Indian fertility centres including Chennai, Mumbai, Bangalore, Delhi, and Hyderabad.
What are the key characteristics of Ovulation Induction?
- Letrozole (aromatase inhibitor): first-line OI drug for PCOS and unexplained infertility; 2.5–7.5mg Days 3–7; stimulates FSH release; predominantly mono-follicular; lower multiple pregnancy risk than clomiphene
- Clomiphene citrate: older first-line agent; 50–150mg Days 2–6; anti-oestrogen; higher multiple pregnancy rate; cervical mucus thinning side effect reduces IUI efficacy
- Gonadotropin injections (FSH ± LH): second-line; 50–75 IU daily; used when oral agents fail; requires careful monitoring; higher OHSS and multiple pregnancy risk
- Monitoring protocol: baseline TVS (Day 2–3); first monitoring scan Day 8–10; then every 1–2 days until trigger; cancel if ≥3 follicles ≥14mm (multiple pregnancy risk)
- Trigger shot: hCG 5,000–10,000 IU or GnRH agonist; given when lead follicle ≥18mm; ovulation 36–40 hours later; timed intercourse or IUI scheduled
- Success rates: letrozole + timed intercourse 15–20% per cycle; letrozole + IUI 20–25% per cycle; cumulative 3-cycle rates 40–55% in anovulatory PCOS
- OHSS risk: low with letrozole (rare); moderate with gonadotropins in PCOS (careful dose titration essential); cancel cycle and withhold trigger if ≥3 large follicles
What does Ovulation Induction involve?
Why does Ovulation Induction matter in fertility?
Ovulation induction is one of the most impactful and cost-effective fertility interventions available — restoring ovulation in anovulatory women (primarily PCOS) with straightforward oral medication. The most important clinical algorithm: letrozole first (PCOS guideline-recommended over clomiphene per NICE, ASRM 2023), dose titrate based on TVS response, add IUI if not pregnant after 3 cycles, escalate to IVF after 3–4 OI-IUI cycles or if bilateral tubal blockage, male factor, or age >38.
What are related terms to Ovulation Induction?
PCOS (Polycystic Ovary Syndrome)
PCOS is a common hormonal disorder where the ovaries produce too many male hormo…
IUI (Intrauterine Insemination)
IUI (Intrauterine Insemination) is a fertility treatment where washed, concentra…
FSH (Follicle-Stimulating Hormone)
FSH (Follicle-Stimulating Hormone) is produced by the pituitary gland. In women,…
LH (Luteinizing Hormone)
LH (Luteinizing Hormone) is produced by the pituitary gland. It triggers ovulati…
Estrogen (Estradiol)
Estrogen (specifically Estradiol or E2) is the primary female reproductive hormo…
FAQs about Ovulation Induction
What drugs are used for ovulation induction?
First-line: Letrozole (aromatase inhibitor) — preferred for PCOS. Second-line: Clomiphene citrate. Injectable gonadotropins (FSH/hMG) are used when oral agents fail or for IUI cycles needing controlled multi-follicular development.
What is the success rate of ovulation induction?
Ovulation induction with timed intercourse achieves 15–25% pregnancy rate per cycle. With IUI, success is 10–20% per cycle. Cumulative success across 3–6 cycles is 40–60% for well-selected patients.
Is ovulation induction safe?
Ovulation induction is safe when monitored. Key risks are multiple pregnancy (twins/triplets) and OHSS. Ultrasound monitoring limits multi-follicle development. Serious OHSS from oral agents is rare.
How many cycles of ovulation induction before IVF?
Most protocols recommend 3–6 cycles of ovulation induction (with timed intercourse or IUI) before escalating to IVF. For women over 37, escalation is typically faster — 3 cycles maximum before IVF.
Can ovulation induction cause twins?
Yes. Oral agents (Letrozole, Clomiphene) carry a 5–10% twin rate. Injectable gonadotropins carry higher multiple pregnancy risk. Monitoring and cancelling cycles with too many follicles significantly reduces this risk.
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