Using Letrozole Tablet (Femara®) for Ovulation induction (OI)

What does letrozole tablet do?

For a lot of women who ovulate irregularly, or not at all, Letrozole tablets can be used to induce regular ovulation, thus increasing their chances of achieving a pregnancy.

How does it work?

Letrozole tablets belong to a class of drugs called aromatase inhibitors. It works by lowering the levels of oestrogen which then enables your ovaries to produce eggs (ovulate).

Ovulation induction is an unlicensed use for letrozole currently, although, it is widely used for ovulation induction and has RCT studies to support its effective use.

What will happen before I start the treatment?

Before starting treatment, we need to make sure that your fallopian tubes are open, that you are immune to Rubella and that your partner’s semen sample is satisfactory. You are also advised to take folic acid supplement (400mcg daily) to help prevent Spina Bifida and other neural tube defects, as well as 10mcg per day of Vitamin D to help maintain calcium levels in yours as well as the unborn child’s bones.

Where will I get my prescription?

You need to start taking letrozole at the beginning of your menstrual cycle. We will prescribe the medication for you, and it will need to be collected from Addenbrookes Hospital Outpatients Pharmacy.

What if you don’t have periods?

If you do not have any periods or your cycles are very irregular you may be given some tablets to make you bleed first (norethisterone tablets). In this case, it is important that you have abstained from intercourse or have used a barrier method of contraception for two weeks. You should then do a home pregnancy test before taking norethisterone tablets.

Instructions for taking letrozole

As we cannot predict exactly when you are going to ovulate it is important to have regular intercourse (every 2 – 3 days) throughout your cycle to maximise your chances of pregnancy.

Day 1: This is the first full day of bleeding. Please telephone the Cambridge IVF 01223 349010 press 4 (nursing) and let us know your period has started (We are opening Monday to Saturday if your period starts on a Sunday, please contact the nurses on Monday morning).

Days 2 – 6: Take the prescribed dose of Letrozole tablets each morning for these five days. The dose usually starts at 2.5mg (1 tablet) per day but you may have been prescribed a higher dose.

Day 21: You need to have a blood test to check your serum progesterone level (this detects if you have ovulated). We can order this on EPIC, and you get it done at the Newmarket Road Park n ride phlebotomy service which is open 9.30-4.30 Monday to Friday. Alternatively, you can get this test at your GP or at our clinic. Once the result is available, please call the clinic for advice on the result.

If day 21 falls at the weekend, then have the test done on the nearest weekday.

Day 28: If your blood result from day 21 suggests you did not ovulate, then a further serum progesterone blood level needs to be taken on this day.

If you do start your period, please telephone the nurses at Cambridge IVF on day 1 and continue as above.

Day 42: If you have not had a bleed by Day 42 you need to do a pregnancy test. Whatever the result, telephone the Cambridge IVF nursing team for advice.

Letrozole tablet dose regime

The starting dose is usually 2.5mg for 5 days day 2 to 6 of your cycle. This is then repeated for the next menstrual cycle. If you have not ovulated on either of these cycles, then your dose will be increased to 5mg for 2 cycles. The Fertility Specialist Nurses at Cambridge IVF will advise you of this. If you have not ovulated on either of these cycles, then you will be advised to increase the dose to 7.5mg for 2 more cycles. You may be given a review appointment in the Outpatient clinic if you are not pregnant after completing 6 ovulatory cycles.

Some information about letrozole

The benefits of taking letrozole tablets are to encourage or regulate ovulation to achieve a pregnancy.

The half-life of letrozole is very short (2 days) compared to clomiphene. This means the medication is metabolized more rapidly and the side effects are less.

Letrozole does not affect the cervical mucus or endometrial (womb) lining as much as clomiphene. This is better for sperm transport in the cervix and a more favourable lining for implantation.

Side effects

Common side effects:

• hot flushes
• dizziness
• fatigue

Other side effects are:

• nausea
• headaches
• bloating
• muscle aches
• blurred vision
• Increased risk of multiple pregnancy (under 5%)
• Ovarian hyperstimulation (caused by producing too many eggs)

Contacting the Cambridge IVF nursing team

If you have any problems or wish to discuss your treatment, please do not hesitate to telephone us on (01223) 349010. We are available 0800-1600hrs Monday to Friday and 0900-1200hrs at the weekends.

It is vital that you communicate regularly with the Fertility Specialist Nurses at Cambridge IVF so that your treatment can be monitored effectively.
Please email or call us at the following points:

Day 1

• Once you have your day 21 progesterone result or 3 days after it is taken
• Again, if day 28 progesterone test is done call with this result
• Day 42 if your period has not started

Cambridge IVF nursing team email: add-tr.ivfnurses@nhs.net

Letrozole treatment schedule

Contact for Cambridge IVF nursing team:

Phone: 01223 349010 Option 4

Email: add-tr.ivfnurses@nhs.net