Anti-oestrogens (clomid)

Clomifene citrate is the oldest and probably the most widely used fertility drug. Normally taken as a pill, it tells your brain that you are not producing enough follicle-stimulating hormone (FSH), which indirectly stimulates your ovaries into producing one or more eggs.

How does using clomifene citrate affect the risk of multiple birth?

Because your ovaries are artificially stimulated to produce more eggs than would be released naturally, this can give a risk of twins of up to 10%, which is 10 times higher than the risk after natural conception, and a 1% risk of triplets.

• hot flushes
• mood swings
• nausea
• breast tenderness
• insomnia
• increased urination
• heavy periods
• spot breakouts
• weight gain

Some experts also think your risk of ovarian cancer may increase slightly if you take it for more than a year.

Treatment with clomifene citrate is often combined with other treatments, such as IVF and intrauterine insemination (IUI).

If you experience unwanted effects with clomifene citrate or have other fertility problems such as polycystic ovary syndrome (PCOS), you may be offered a different but similar drug called tamoxifen.

Like clomifene citrate, tamoxifen may increase your chances of getting pregnant but also increases your risk of multiple pregnancy and birth.

What are my options?

If you are using fertility drugs such as clomifene citrate or tamoxifen, you should discuss the following with your clinician:

• Monitoring: This is to check on the number of follicles (and hence eggs) that develop.
• Dosage: The aim is to maximise your chance of becoming pregnant while keeping your risk of multiple pregnancy and side-effects to a minimum.