PCOS and Fertility: Causes, Impact on Conception & Treatment Options

PCOS and Fertility: What You Need to Know

Polycystic Ovary Syndrome (PCOS) is the most common hormonal disorder affecting reproductive-age women, diagnosed in 6–12% globally and up to 20–22% of Indian women. It is also the most common cause of anovulatory infertility — but with the right treatment, most women with PCOS successfully conceive.

How PCOS Affects Fertility

The primary mechanism of PCOS-related infertility is anovulation — failure to ovulate regularly. Without ovulation, no egg is released, and conception cannot occur naturally.

Why PCOS causes anovulation:

• Elevated LH:FSH ratio — disrupts normal follicle maturation
• Elevated androgens (testosterone) — arrests follicle development at the small follicle stage
• Insulin resistance — raises insulin levels, which stimulate further androgen production from the ovaries
• Elevated AMH — inhibits follicle selection and progression to ovulation

The result: many small follicles (the "polycystic" appearance on ultrasound) that never reach the dominant follicle stage and ovulate.

Additional fertility impacts of PCOS:

• Endometrial hyperplasia: Chronic anovulation with no progesterone exposure can cause endometrial thickening and irregular bleeding, occasionally requiring treatment before fertility treatment
• Miscarriage risk: Women with PCOS have a slightly elevated miscarriage rate (30–50% higher), partly attributed to elevated LH, insulin resistance, and elevated androgens
• OHSS risk: Women with PCOS are at higher risk of ovarian hyperstimulation syndrome (OHSS) during IVF due to high antral follicle counts and high AMH
• Metabolic complications: Insulin resistance, type 2 diabetes, and obesity (in ~50–60% of PCOS patients) further complicate fertility

Treatment for PCOS-Related Infertility

The International Evidence-Based PCOS Guideline 2023 (ASRM/ESHRE/NHMRC) recommends a stepwise approach:

Step 1 — Lifestyle modification (first-line for overweight/obese PCOS) A 5–10% weight reduction in overweight women with PCOS can restore ovulation in up to 55% of cases (Palomba et al, JCEM 2014). Even without significant weight loss, caloric restriction improves insulin sensitivity. Mediterranean diet pattern is recommended.

Step 2 — Letrozole (first-line ovulation induction, PCOS 2023) Letrozole (an aromatase inhibitor) replaced clomiphene as the first-line ovulation induction agent in the 2023 PCOS guideline. A landmark NEJM 2014 trial (Legro et al) showed letrozole achieved significantly higher live birth rates than clomiphene (27.5% vs 19.1%) in anovulatory PCOS.

Letrozole dose: 2.5–7.5mg from day 3–7 of cycle. Monitoring ultrasound recommended (to detect multi-follicular response).

Step 3 — Metformin (adjunctive treatment) Metformin improves insulin sensitivity and, in combination with letrozole, improves ovulation rates further. The 2023 guideline recommends metformin as adjunctive to letrozole, not standalone first-line. Standard dose: 1500–2550mg daily.

Step 4 — Gonadotropin injections (FSH injections) For women who fail to ovulate with oral medications. Low-dose step-up FSH protocol is used to achieve mono-follicular development. Requires careful monitoring to prevent multi-follicular response and OHSS.

Step 5 — Laparoscopic Ovarian Drilling (LOD) A surgical procedure where electrocautery or laser punctures multiple follicles on each ovary, reducing androgen production and restoring ovulation. Success rates comparable to 3–4 cycles of FSH injections. Recommended when gonadotropins fail or are unavailable. Effect lasts 1–2 years.

Step 6 — IVF Recommended when simpler treatments fail after 6–12 months, or when there are additional fertility factors. Key PCOS-specific considerations for IVF:

• OHSS prevention: GnRH antagonist protocol + GnRH agonist trigger (instead of hCG) dramatically reduces OHSS risk. Freeze-all strategy (no fresh transfer) with FET in subsequent cycle.
• Stimulation protocol: Low starting FSH doses (100–150 IU). Aggressive monitoring.
• Metformin co-treatment: May reduce OHSS risk during IVF (Palomba et al, 2014)
• Expected response: Women with PCOS typically have higher egg yields — 15–25 eggs is common.

PCOS and IVF Outcomes

Despite higher OHSS risk, women with PCOS have excellent IVF outcomes when OHSS is managed. Per ESHRE 2023 data: women under 35 with PCOS achieve live birth rates of 45–55% per frozen embryo transfer — comparable to or better than normo-ovulatory women — because they produce more eggs.

Managing PCOS for a Healthy Pregnancy

Women with PCOS are at higher risk of:

• Gestational diabetes (recommend oral glucose tolerance test at 24–28 weeks)
• Pregnancy-induced hypertension
• Pre-eclampsia
• Preterm birth

Early antenatal registration and monitoring is recommended for all PCOS pregnancies.

Reference: International Evidence-Based Guideline for PCOS, ASRM/ESHRE/NHMRC 2023. Legro RS et al, Clomiphene, Metformin, or Both for Infertility in the Polycystic Ovary Syndrome, NEJM 2014.