Latest version of Pill 'three times more likely to cause blood clots'

WOMEN taking third generation contraceptive pills are up to three times more likely to suffer a blood clot than those using older varieties, according to research released today.

Scientists say doctors should prescribe the lower risk preparations containing the hormone levonorgestrel as the "first line choice" for women.

Third generation pills include the brand Yasmin while the older ones include Microgynon.

In a study published online today in the British Medical Journal, Dr Susan Jicks, of Boston University School of Medicine, calls for a "systematic review" of which contraceptive pills are prescribed.

However, Dr Anne Szarewski, clinical consultant and spokeswoman for the Faculty of Sexual and Reproductive Health at the Royal College of Obstetricians and Gynaecologists, said the study, and a previous one it compares its findings with, were both "incredibly flawed".

Dr Szarewski said they failed to take into account that newer pills were being given to "riskier" women - such as those with a higher body mass index, smokers or women who had a family history of venous thromoembolism (VTE) in which a blood clot forms in the vein.

The debate started in October 1995 when scientists warned that women taking the third generation pill were at greater risk of developing blood clots in the deep veins of the legs or the pelvis and which can be fatal if they move inside the circulatory system and lodge in the lungs.

Many women then stopped taking their contraceptive, resulting in a boom in unwanted pregnancies and an 8 per cent rise in abortions. Other experts later disputed the risk, saying it was much lower than estimated.

In the first study, based on US medical data, the researchers found a twofold increased risk of a non-fatal blood clot in women using pills containing the hormone drospirenone compared with women using the older ones which have levonorgestrel. This risk remained even after taking account of other possible causes.

The second study, using data from the UK General Practice Research Database, found a threefold increased risk of a first non-fatal blood clot in women using drospirenone pills oral compared with those on the levonorgestrel ones.

A spokeswoman for the Scottish Government said: "All women taking the contraceptive pill are monitored regularly by health professionals."

BACKGROUND

THE hormone oestrogen in the Pill may cause a person's blood to clot more readily.

If a blood clot develops it could cause deep vein thrombosis (DVT).

However, the risk is very small - around 15 out of 100,000 women taking the Pill for a year will develop it, compared to five to ten cases in women not on the Pill.

Before prescribing the Pill, GPs should check whether a woman has any DVT risk factors. These include being aged over 35, being obese or a smoker, having a family history of DVT, having high blood pressure or getting severe migraine attacks.

The Pill should not be prescribed if you have two or more risk factors. Doctors advise patients on the Pill to stop taking it four weeks before a major operation.