PCOS and Getting Pregnant
PCOS causes most anovulatory infertility. The good news: most women with PCOS do get pregnant, often with relatively simple treatment.
How PCOS Affects Fertility
Polycystic ovary syndrome (PCOS) affects approximately 8-13% of women worldwide of reproductive age. In Singapore, estimates are similar, with some studies suggesting rates up to 15-20% in certain ethnic groups. PCOS is the leading cause of anovulatory infertility - meaning infertility caused by not ovulating regularly or at all.
In PCOS, elevated androgens (male hormones) and disrupted LH/FSH ratios interfere with follicle development. Follicles begin growing but do not complete ovulation. They accumulate in the ovary as small cysts (not true cysts, but immature follicles). Without ovulation, there is no egg to fertilise.
Irregular or absent periods are the main clue. If your cycles are consistently longer than 35 days or unpredictable, PCOS is a likely explanation and you should see a gynaecologist for diagnosis.
How PCOS is diagnosed (Rotterdam Criteria)
PCOS is diagnosed if you have 2 of these 3: (1) irregular or absent periods, (2) elevated androgens (blood test or physical signs like excess hair or acne), (3) polycystic-appearing ovaries on ultrasound (12 or more follicles per ovary, or ovarian volume over 10mL). Other causes of irregular periods (thyroid, high prolactin) must be ruled out.
The PCOS Fertility Treatment Ladder
Most women with PCOS do not need IVF to conceive. Treatment follows a step-up approach, starting with the least invasive options.
Lifestyle changes (first line for overweight PCOS)
Even a 5-10% reduction in body weight can restore regular ovulation in overweight women with PCOS. This is not about being thin - it is about the specific effect of weight on androgen and insulin levels. Low-GI diet reduces insulin resistance, which is central to PCOS. Regular exercise also improves insulin sensitivity and cycle regularity.
Ovulation induction - Letrozole (first choice)
Letrozole (an aromatase inhibitor) is now the preferred first-line drug for ovulation induction in PCOS. It is taken on days 3-7 of the cycle (or a progestogen-induced cycle if you do not have periods). It stimulates FSH release to trigger ovulation. Success rate per cycle: 15-25%. 3-6 cycles are commonly tried before moving on.
Clomiphene (Clomid) - second oral option
Clomiphene was the standard for decades. Letrozole has better success rates in PCOS and fewer multiple pregnancy risks, so Clomid is now second-line. Still effective and inexpensive ($20-60/cycle).
Injectable gonadotrophins + IUI
If oral drugs fail, daily FSH injections with careful monitoring offer higher success rates (20-30% per cycle) but higher multiple pregnancy risk. Combined with IUI for better delivery of sperm.
IVF
Reserved for PCOS patients where simpler treatments have failed, or where there are additional factors (tubal disease, male factor). Success rates per cycle: 35-50% for women under 35. PCOS women typically have a good ovarian response to stimulation but need careful dose monitoring to avoid OHSS (ovarian hyperstimulation syndrome).
What About Metformin?
Metformin is an insulin-sensitising drug sometimes prescribed for PCOS. It can help restore regular periods in some women, particularly those with significant insulin resistance. However, as a standalone fertility treatment, metformin is less effective than letrozole and is not recommended as first-line treatment for ovulation induction in PCOS by most current guidelines.
Metformin may be continued during fertility treatment (and into early pregnancy) for women with PCOS and diabetes or significant insulin resistance. Discuss with your gynaecologist whether it is appropriate for your situation.