Royal Prince Alfred Hospital
Fertility Unit
Royal Prince Alfred Hospital

Ovulation induction (OI)

What is OI?

Ovulation induction (OI) is controlled ovarian stimulation using low doses of follicle stimulating hormone (FSH). This is used to increase the number of follicles that develop fully, thereby causing ovulation in those patients who do not normally ovulate or who ovulate rarely. We monitor the body's response closely with blood tests and ultrasounds. When the dominant follicle is the right size, ovulation is triggered with an injection of human chorionic gonadotrophin (hCG), and we will advise you to have sexual intercourse.

Who is it for?

Ovulation induction may be recommended for who women who have normal tubes but who rarely or never ovulate, and whose partners have a normal semen analysis. For women who do ovulate regularly, ovarian stimulation can be used to increase the chance of pregnancy by increasing the number of follicles.

Drugs used in OI?

  • Recombinant follicle stimulating hormone (FSH)
  • Human chorionic gonadatrophin (HCG/Pregnyl)

Possible complications

Multiple pregnancy – using FSH to induce ovulation for getting pregnant naturally (as opposed to IVF) can be difficult, because of the risk of stimulating too many follicles and having a multiple pregnancy. This is why we monitor the body's response with blood tests and ultrasounds.  If too many follicles are present, your cycle will be cancelled and we will advise you to avoid sexual intercourse because of the high risk of a multiple pregnancy (including triplets or more). We may convert your cycle to IVF, if you have signed the appropriate consent forms.

Ovarian hyperstimulation – Overstimulation of your ovaries (or hyperstimulation) is another complication that could arise as a result of this treatment.

Pregnancy rates

Pregnancy rates depend primarily on the age of the woman and range from around 10% to 35% per month, or 40% to 50% over a six-month course of treatment in women under 38.