Recent studies on birth control pills have been linking them to increased risk of heart attacks in women using these pills. However, a new study published by Walter Spitzer, an emeritus professor of epidemiology and his colleagues, has contradicted previous studies by stating that women who take third-generation birth control pills containing desogestrel or gestodene show no increased risk for heart attack compared to women who do not take birth control pills.
The researchers used an approach called meta-analysis, which involves using subjects from many studies and combining the results to achieve a type of statistical power superior to what individual studies can provide.
The study found that one in 100,000 women taking third generation birth control pills had a heart attack which is almost the same as for women who do not take the pills. Spitzer points out that controversies about third generation oral contraceptives have focused on blood clots in the veins, while neglecting to illuminate the safety of newer birth control pills on arteries.
Oral contraceptives of the first generation used very high doses of estrogen, a hormone which suppresses ovulation. The next generation of pills however lowered levels of estrogen and added forms of another hormone called progestin ( norgestrel or levonorgestrel). Progestins inhibit ovulation by suppressing a hormone in the pituitary gland and also cause mucus to thicken on the cervix, forming a barrier to fertilization of the egg by the sperm. The third-generation pills, which are the latest in the market, changed the type of progestin to desogestrel or gestodene so that cholesterol-raising effects and tendency to promote weight gain were reduced. This has helped third generation pills to cut heart attack risk in half in comparison to second-generation pills.
A study released in early 2002 which was carried out at University Medical Center in Utrecht, the Netherlands showed that women taking no pills showed a rate equivalent to 30 strokes per 100,000 compared to about 60 strokes per 100,000 for women taking second or third-generation pills, still somewhat less than the risk of stroke during pregnancy. However, Spitzer argues that the study lacked sufficient statistical power to be conclusive. He says that the finding may be true for young healthy women who have pre-plaque-deposition and have whistle-clean coronaries, but those are probably not the ones who are going to have a heart attack.
The finding against increased risk of heart attacks in women taking birth control pills is further strengthened by Roger Blumenthal, director of preventive cardiology at Johns Hopkins Hospital in Baltimore. He points out that the earlier study in Netherlands does not see any association of third generation oral contraceptives with cardiac events which makes the study insufficient to deny women birth control pills. However, Bluementhal also adds that birth control pills are not given to women who fall in the high risk category for a heart attack, such as smokers or some with elevated blood pressure.