Controlled ovarian hyperstimulation is a technique used in assisted reproduction involving the use of fertility medications to induce ovulation by multiple ovarian follicles. These multiple follicles can be taken out by oocyte retrieval (egg collection) for use in in vitro fertilisation (IVF), or be given time to ovulate, resulting in superovulation which is the ovulation of a larger-than-normal number of eggs, generally in the sense of at least two. When ovulated follicles are fertilised in vivo, whether by natural or artificial insemination, there is a very high risk of a multiple pregnancy.
In contrast, when referring to treating menstrual disorders, such as oligoovulation or anovulation, the preferred term is ovulation induction. In this article, unless otherwise specified, hyperstimulation will refer to hyperstimulation as part of IVF.
Response predictors determine the protocol for ovulation suppression as well as dosage of medication used for hyperstimulation. Response prediction based on ovarian reserve confers substantially higher live birth rates, lower total costs and more safety.
It is commonly agreed not to exclude anyone from their first IVF attempt only on the basis of poor results on response predictors, as the accuracy of these tests can be poor for the prediction of pregnancy.
The response to gonadotropins may be roughly approximated by antral follicle count (AFC), estimated by vaginal ultrasound, which in turn reflects how many primordial follicles there are in reserve in the ovary.