Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women, associated with a characteristic ovarian appearance at ultrasound scan, hyperandrogenism, and ovulatory disorders. The pathogenesis appears to be mainly related to reduced insulin sensitivity in peripheral tissues, leading to hyperinsulinaemia. There is a wide variation in the severity of PCOS symptoms. Women with PCOS are believed to be predisposed to a variety of complications in pregnancy. We present a summary of the evidence surrounding these claims and discuss the weaknesses of the available to date studies.