Polycystic ovary syndrome and fertility

Polycystic ovary syndrome is a common endocrine condition defined by irregular ovulation, raised androgens, and polycystic ovaries, with insulin resistance as a central mechanism in many cases. The treatment follows from the mechanisms.

Weight and insulin resistance. Weight loss of 5-10% restores ovulation in a substantial share of women with PCOS who are overweight, and this is the intervention with the best evidence and the one that costs nothing. Lifestyle intervention is first-line in every guideline.

Inositol (myo-inositol, often with D-chiro-inositol) has multiple small randomised trials showing improved insulin sensitivity, lower androgens, and improved ovulation, and it is well tolerated. It is the best-supported supplement for PCOS, and it is used as an adjunct to lifestyle measures rather than instead of them.

Metformin improves insulin sensitivity and restores ovulation in some women; it is prescribed and has a long evidence base. Not for use in pregnancy without advice.

Vitamin D — low levels are common in PCOS and correcting a deficiency is reasonable; the evidence for ovulatory benefit from supplementation alone is weak.

Letrozole is now the first-line ovulation induction agent for PCOS and is more effective than clomiphene. This is a specialist decision, and it is the thing that matters for fertility.

What has weak evidence and is sold anyway. Many herbal blends marketed for PCOS or for fertility. Some individual herbs have small trials (spearmint for hirsutism, cinnamon for glycaemia), and they are adjuncts.

The frame. PCOS is associated with type 2 diabetes, the metabolic syndrome, and endometrial hyperplasia from unopposed oestrogen in women who do not ovulate regularly. That last one is a cancer risk and it is the reason irregular periods in PCOS should be managed rather than tolerated — the endometrium needs to shed, either through ovulation or through a prescribed withdrawal bleed.

Fertility generally. For both partners, the interventions with evidence are stopping smoking, reducing alcohol, achieving a healthy weight, treating thyroid disease, adequate folate, and treating specific causes (anovulation, tubal disease, male factor). The male factor is present in a substantial share of cases, which is why both partners are assessed. Supplements marketed for male fertility — various antioxidants — have small and inconsistent trial evidence at best.