Bath Fertility Centre: Ovulation Induction
Ovulation Induction
In this section:
What is ovulation induction and follicle tracking?
Ovulation induction (OI) and follicle tracking involves using fertility drugs to stimulate the development of a few follicles which are ‘tracked’ or monitored by ultrasound scan. When sufficient follicles are judged to have reached the optimum size, a final injection is given to trigger ovulation, and intercourse is planned to coincide with ovulation to maximize the chance of sperm reaching a ripe egg for fertilisation to occur. Although the procedure itself is straightforward, the timing is very important.
Ovulation induction is suitable for couples where the female partner may not ovulate reliably but has normal healthy tubes, and the male partner has a normal or nearly normal semen analysis.
What is involved in this treatment?
Before starting your treatment an ultrasound scan is carried out to check the appearance of your ovaries, and providing this is normal you would start injecting a low dose of fertility drugs to stimulate the production of one or more follicles.
A week after you have started your injections, you will have another scan to check how many follicles you are growing and their size. We are aiming for a maximum 3 large follicles and no more than 2 smaller. If your scan shows this, you will be asked to give yourself a final injection of a different hormone which will make you release the egg(s) 34 - 40 hours later. Intercourse will be timed to coincide with this.
If you have grown more than the required number of follicles you may have to stop treatment. This is because there could be a high risk of multiple pregnancy occurring if treatment were to continue. See below for more about associated risks.
How successful is it?
Pregnancy rates for ovulation induction are around 10 - 15% per treatment cycle. This is lower than with IVF/ICSI as we are not able to be certain that fertilisation has taken place following ovulation and intercourse. For this reason OI is usually limited to 3 cycles before we review your progress.
Are there any risks associated with ovulation induction?
Occasionally some women over-respond to the fertility drugs, producing too many follicles. If intercourse were to take place after several large follicles have ovulated there would be a risk of a multiple pregnancy involving more than 2 embryos. We would therefore stop your treatment immediately and advise you that you must either take contraceptive precautions (use a condom) or abstain from intercourse until you have your next period. For subsequent treatment cycles the amount of drugs would be reduced to try to make you grow fewer follicles. In rare cases OHSS may occur and treatment would be stopped and restarted when safe to do so.
Some planned ovulation induction treatments need to be cancelled due to lack of response to the drugs used to stimulate follicle production. In this case the amount of drugs you take would be adjusted to try to make you grow more follicles in another treatment cycle.