NEW YORK, Jun 16 (Reuters Health) - While birth control pills have been
linked to a risk of blood clots, new research suggests that more women than
commonly thought may die of Pill-related clots in the lungs.
Although the risk is very low--about 10.5 deaths per million women each
year--researchers in New Zealand say the potential for a lung blood clot, or
pulmonary embolism, should not be regarded as insignificant.
In a study of all New Zealand women aged 15 to 49, Dr. David C. G. Skegg and
his colleagues at the University of Otago Medical School, found that oral
contraceptive users were nearly 10 times more likely than women not on the Pill
to die of a pulmonary embolism.
Their findings are published in the June 17th issue of The Lancet.
The number of deaths was small; just 29 women were confirmed to have died of
a pulmonary embolism between 1990 and 1998. Seventeen of the women, or 65%, were
Pill users when they died. When Skegg and his colleagues compared these women
with 111 healthy 'control' subjects, they found that 23% of controls were
currently using oral contraceptives.
This low death risk among oral contraceptive users was, however, higher than
expected, according to Skegg's team. And, they write, their estimate of 10.5
deaths per million women each year "is probably conservative." One reason may be
the widespread use of "third-generation" birth control pills that contain
desogestrel or gestodene as part of their hormone combination.
These findings support the use of "second-generation" pills that contain
levonorgestrel, according to an editorial accompanying the report. Neil R.
Poulter of the Imperial College School of Medicine in London writes that the use
of lower doses of estrogen in birth control pills has not cut the risk for blood
clots.
The link between oral contraceptives and pulmonary embolism remains a
concern, Poulter notes, "not least because the diagnosis is easily missed and
because the complication is a side effect of a drug prescribed by the medical
profession for young healthy women."
