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Ovulation induction using Metformin - patient information

Patient information A-Z

Cambridge IVF logo and strapline 'creating your future'.

Women with Polycystic Ovary Syndrome (PCOS) have changes in the way in which their body handles sugars and the way in which insulin works to metabolise them. Some of these changes may either cause, or may make these symptoms worse. One way to overcome these changes is to lose weight. This can be done by modifying diet and by taking more exercise. An additional method is the use of drugs to make the body more sensitive to insulin. One such drug is Metformin which you have been prescribed by the doctor today. The ultimate aim is to induce regular ovulation and periods, thus increasing your chances of conceiving. As we cannot predict exactly when you are going to ovulate, it is important to have regular intercourse (every 2 – 3 days) throughout your treatment, in order to maximise your chances of pregnancy.

How to take Metformin:

Before starting treatment with Metformin you must have had an investigation to confirm that your fallopian tubes are open and your partner must have had a recent, satisfactory semen analysis test. You will have been asked to have various blood tests. The results of these must have been received and be found to be within normal ranges.

You may be given a prescription for Metformin from your Consultant or one of the Fertility Specialist Nurse’s will arrange delivery of the drug to your home. Further supplies may be prescribed for you by your GP – please speak to the Cambridge IVF Nurses and we can arrange that for you. Metformin treatment does not have to be started with a period, therefore, even though this is unlikely, it is important to ascertain that you are not pregnant before commencing treatment. Before you take any tablets you must have abstained from unprotected sexual intercourse for two weeks and have had a negative result from a home pregnancy test. You will also be given request forms for blood tests to be used in order to confirm ovulation once cycles have become established.

Instructions for taking Metformin:

When you are ready to start treatment, please telephone the nurses at Cambridge IVF to inform them of the date. Start taking the tablets according to the following regime:

  • Start with 500 mg with evening meal for 7 days.
  • 500 mg with breakfast and 500 mg with evening meal for 7 days
  • 500 mg with breakfast and 1000 mg with evening meal for 7 days

1000 mg with breakfast and 1000 mg with evening meal and continue until advised to stop.

Side effects

Common problems encountered by patients taking Metformin are nausea and stomach upset, other complaints may also include stomach cramping and diarrhoea. These symptoms can be overcome in two ways; 1) take Metformin with food, 2) reduce Metformin dose to 500 mg daily for 2 weeks until symptoms improve. These side effects are the most common reason for patients stopping the treatment. However if you are made aware that these symptoms may occur, and you reduce your dose accordingly, hopefully treatment can continue.

(Record your doses and any adverse symptoms and details of bleeding on the form provided).

Please call the Fertility Nurse Specialists on 01223 349010 to inform them of your periods so that you can be given advice. If you have to leave a message remember to leave your full name, treatment and a contact telephone number and we will call you back as soon as possible.


Your progress will be reviewed after completing week 8. We will require information about side effects and dates on which any bleeding has occurred. It is therefore important to update your records daily.

Predicting ovulation:

Once a bleeding pattern has become established you may be advised with a date on which to start daily urine testing using LH sticks (e.g. Clearplan or ClearView) which can be obtained from high street chemists. This test predicts ovulation so that intercourse can be timed accordingly. Please inform the nurses at Cambridge IVF of a positive result. If you have to leave a message please leave your full name, treatment and contact telephone number and we will call you back as soon as possible.

Confirming ovulation:

Ovulation can be confirmed by measuring Progesterone levels in the blood. This should be done in the middle of the second half of the cycle. The nurses at Cambridge IVF will inform you of the date of this test. You will need to call us again two working days later in order to obtain the result.

Pregnancy testing

If it appears that you have ovulated and you have not had a period 3 weeks following the blood test, you should do a home pregnancy test. Please inform the Fertility Nurse Specialists of the result. If the results are negative you will be advised to continue with your treatment.

Contacting the nurses:

If you have any problems, or wish to discuss treatment, please do not hesitate to telephone us on 01223 349010 and we will be happy to help you. The nurses are available Monday-Friday 0800-1700 and 08:00-12:00 on a Saturday. Urgent messages will be replied to within 24 working hours, non-urgent messages within 2-3 working days.

It is vital that you communicate regularly with the Fertility Nurse Specialists so that your treatment can be monitored effectively. If you have your blood tests at your GP surgery please be sure to contact us to give us the results.

There have been recent studies performed which show no problems linked to Metformin when taken during pregnancy and no adverse effects or fetal abnormalities have been recorded, however at present our advice is to STOP Metformin once pregnancy has been confirmed.

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Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151