When FSH is given in larger amounts than would occur in a natural menstrual cycle it results in more than one egg being ripened and matured. Here are three reasons why FSH is used in fertility treatments.

1. Sometimes if you are not ovulating, FSH is given in an amount roughly equal to that of a natural menstrual cycle and this is called ovulation induction. The goal is to produce one or occasionally two ripe eggs only.
2. At other times the intention may be to produce 2 to 3 eggs and this is called superovulation. This is often used to treat unexplained infertility and infertility after treatment of endometriosis. This may be combined with placement of your partner’s sperm in your uterus (insemination). This is not very commonly performed as there is a risk of twinning and higher-order multiple pregnancies such as triplets and quadruplets.
3. FSH is used is in IVF (in vitro fertilisation). The intention here is to produce 10 to 15 eggs with the aim of fertilising them outside the body. The reason why so many eggs are necessary is that the process of IVF is relatively inefficient and the more eggs that are available for fertilisation, the more likely pregnancy is to occur.

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