Anovulation as cause of infertility and novel methods of ovulation induction

Abstract

Infertility is known to affect one in six couples. Ovulatory dysfunction is a common underlying cause and is seen in approximately 38% of couples seeking infertility treatment. Polycystic ovary syndrome was the commonest underlying cause of anovulation and was seen in nearly 60% women. Hypogonadotropic hypogonadism and ovarian failure are uncommon causes of anovulation seen in only about 1-2% of women with anovulation. Clomifene citrate is the commonest medication used for induction of ovulation. It is successful in achieving ovulation in over three quarters of women with WHO group II anovulation. However, factors such as hirsutism, a high antral follicle count and a high LH:FSH ratio are associated with clomifene resistance. Aromatase inhibitor, letrozole, is a novel medication for induction of ovulation. It is successful in achieving ovulation in nearly 75% of women who respond to clomifene and 25% of women with clomifene resistance. Factors associated with resistance to letrozole included a high day2 LH level, hirsuitism and clomifene resistance had the highest association. The use of letrozole for augmentation of ovulation, in comparison to clomifene, resulted in a higher endometrial thickness and a trend towards monofollicle development. Gonadotropin (FSH) is used in induction of ovulation among women with resistance to oral medication. A low-dose step down regimen of rFSH, in comparison to a low-dose step-up regimen, showed a shorter duration of treatment, with no significant reduction in the total drug requirement. These findings have improved our understanding of different modes of induction of ovulation, which helps in further research and clinical practice.