Anti-oestrogens - managing the risks

The likelihood of a twin pregnancy resulting from clomifene treatment is approximately 10%. Hospitals and fertility units should have their own protocols for the safe use of clomifene citrate, including ultrasound monitoring, etc. Monitoring should also take place where clomifene citrate is prescribed by a GP.

What is the official guidance?

The NICE Guidelines (Clinical Guideline 11, February 2004, paras 1.6.1.1–4 ) on clomifene citrate and multiple births state that:
  • Women with World Health Organisation (WHO) Group II ovulation disorders (hypothalamic pituitary dysfunction) such as polycystic ovary syndrome, should be offered treatment with clomifene citrate (or tamoxifen) as the first line of treatment for up to the first 12 months because it is likely to induce ovulation.
  • Women should be informed of the risk of multiple pregnancies associated with both clomifene citrate and tamoxifen.
  • Women with unexplained fertility problems should be informed that clomifene citrate treatment increases the chance of pregnancy, but that this needs to be balanced by the possible risks of treatment, especially multiple pregnancy.
  • Women undergoing treatment with clomifene citrate should be offered ultrasound monitoring during at least the first cycle of treatment to ensure that they receive a dose that minimises the risk of multiple pregnancy.

See the NICE website for more information.

Minimising the risks

To balance the risks of multiple pregnancy with the chance of a positive outcome, the following approach is recommended:
  • Explain to patients the risks of multiple pregnancy associated with clomifene citrate and give details of the types of problems that accompany multiple pregnancies and births (see What are the risks?).
  • Follow up with written information (leaflets, brochures, etc).
  • Having decided that treatment with clomifene citrate is appropriate, to minimise the risk of multiple pregnancy, keep the prescription to a minimum. The normal prescription of clomifene is 50mg for the first cycle, rising to 100mg, with a (rare) maximum of 200mg. It is normally prescribed over three cycles, with a maximum of six cycles.
  • Offer ultrasound monitoring for at least the first treatment cycle to ensure dosage is appropriate (that is, it should increase the chances of pregnancy while minimising the risk of multiple pregnancy).