Newer third generation birth control pills such as desogestrel or gestodene may not be safer for your heart than their predecessors, as originally predicted.

In a review of the evidence so far, Dr Paul O'Brien, senior clinical medical officer in clinical effectiveness at St Charles Hospital in London says that studies into the heart risks for women on the newer pill have produced mixed results. At best, in those women who have existing hypertension no difference between third and second generation pills has been found. More worrying, four well designed studies have shown that the third generation Pill doubled the risk of venous thromboembolism over that of second generation pills.

In a recent Dutch study, researchers noted a 16 per cent increase in hospital admissions for venous thrombembolism, which correlated with the increase in prescriptions for third generation Pills (BMJ, 1999; 319: 832-3)

Dr O'Brien, a paid consultant to the legal team representing women who developed a venous thrombosis while using third generation oral contraceptives, comments that although the increased risk of venous thrombosis with third generation pills is "real and measurable", this has not changed guidelines for prescribing this Pill. "The Medical Commission recently confirmed the excess risk but removed restriction on prescribing and left it to clinical judgement and patient preference," he said (BMJ, 1999; 319: 795-6)