By Amy Norton
NEW YORK, Aug 18 (Reuters Health) - Despite a 1995 "scare" over the safety
of the newest wave of birth control pills, UK researchers now say these concerns
were unfounded. So-called 'third generation' pills seem to be no more likely
than their previous incarnation to trigger blood clots in women, the
investigators report.
Use of third generation contraceptive pills fell sharply in the UK after
research suggested they were twice as likely as second generation pills to cause
blood clots in the lungs or veins--even though the risk of such clots is still
very low among birth control pill users.
However, the decline in the use of third generation pills has created no
drop in blood clots among women on the Pill, researchers report in the August
19th issue of the British Medical Journal.
The safety of the newest generation of oral contraceptives is "no different
than the older ones," lead researcher Dr. Richard D.T. Farmer of the University
of Surrey told Reuters Health.
Third and second generation birth control pills differ in the type of
progestin they contain. Both generations combine the hormone with low doses of
estrogen; second generation oral contraceptives, which were introduced in the
late 1970s, contain a synthetic hormone called levonorgestrel, and third
generation oral contraceptives contain desogestrel or norgestimate.
According to Farmer, the Pill's link to a risk for blood clots was
originally attributed to its estrogen content. That came into question, he said,
in 1995, when the UK advised women that third generation pills carried a higher
risk for blood clots.
Farmer's team found that between 1995 and 1998, use of third generation
pills fell from 54% of UK women on the Pill to just 14%. Yet the incidence of
blood clots did not follow suit, and in fact rose to a higher-than-expected
level. The number of cases--97--was still quite low, however.
These findings, Farmer pointed out, reinforce the belief that the Pill's
estrogen level is indeed behind its association with blood clots. This link is
one reason today's Pill contains much lower doses of estrogen compared with the
first generation of oral contraceptives.
The decision about which Pill generation to take should depend on the
individual woman, Farmer explained. Some women, for example, may prefer third
generation pills because they help clear up acne, he noted.
"We now can give women genuine choices," Farmer said, "and one should treat
each woman as an individual."
