What Is PCOS? How Can It Affect Fertility?
Polycystic ovarian syndrome (PCOS) is the most common hormonal disorder in reproductive age women. Depending on nationality, it is present in up to one-in-five women and even more frequently in women with fertility problems. PCOS is also one of the most common causes of menstrual irregularities, infertility, and hirsutism, affecting between 5% and 10% of women of reproductive age worldwide. Despite an enormous effort to define its cause, the etiology of PCOS remains unclear, and there is no definite cure at this time.
PCOS is clearly a heterogeneous disorder which often has a familial (genetic) basis. Infertility associated with PCOS has been attributed to numerous factors, including dysfunctional gonadotropin pituitary secretion, peripheral insulin resistance, elevated adrenal and/or ovarian androgen (male hormone) levels, and dysfunction of several growth factors. Women with this condition are often obese and insulin resistant. The compensatory hyperinsulinemia further stimulates ovarian androgen production which may be detrimental to egg maturation, and there is a clear link between the degree of insulin resistance and anovulation.
PCOS is also a significant long-term health risk for women, thus necessitating vigilance through regular annual examinations (non-insulin dependent diabetes mellitus, hypertension, hypercholesterolemia, cardiovascular disease and endometrial cancer). Whereas PCOS-related infertility is usually manageable through the use of fertility drugs, lifestyle changes (diet and exercise) remain a mainstay of long-term therapy.
Although there is no known single cause of PCOS, we know that insulin plays a pivotal role. Women with higher than normal insulin levels often develop PCOS, and many treatments that lower insulin levels improve fertility in women with PCOS. Any condition that causes insulin levels to rise (like diabetes or obesity) will create or worsen PCOS. Most commonly, women with PCOS have insulin resistance. It is the sensitivity of the ovary to insulin and other hormones that prevents the follicles from producing mature healthy eggs.
Recently, improvement in ovulation rates, circulating androgens, pregnancy rates and perhaps even first-trimester miscarriage rates have been observed when insulin sensitizers like metformin are used to correct the underlying insulin resistance.
Most patients with PCOS are young and have excellent pregnancy rates with oral clomiphene. Those that require more aggressive treatments with injectable medications probably represent a subgroup of PCOS patients with severe ovarian dysfunction. These women often have explosive response to gonadotropins which can result in serious complications like Ovarian Hyperstimulation Syndrome (OHSS) and high order multiple births. In those women, the ability to perform “prolonged coasting” and selectively transfer fewer embryos during IVF offers a clear advantage over standard gonadotropin injections.