What are the risks of taking combined oral contraceptive pills?

What are the risks of taking the birth pill?

The early combined oral contraceptive pills contained 150 mg of the oestrogen mestranol together with norethynodrel which is a progestogen. The first report of thromboembolism (a blood clot forming in a vein within the leg or pelvis and then travelling to the lungs) in association with the combined oral contraceptive pill came soon after the combined oral contraceptive pills were introduced. The pharmaceutical industry has made enormous efforts to reduce the risks associated with the oral contraceptive pills whilst maintaining their contraceptive effectiveness. Essentially there have been two avenues that have been explored. Firstly, the amount of oestrogen in the combined oral contraceptive pill has been reduced and secondly newer progestogens have been developed.

The oestrogen in the combined oral contraceptive pill reduces LH and FSH production and therefore suppresses follicular development and ovulation (Q 2.3). There has been concern that reducing the amount of oestrogen in the combined oral contraceptive pills could lead to contraceptive failure. Over the years it has been found that the lowest dose of oestrogen that remains effective is much lower than originally contemplated. The original 150 mg was reduced to 100mg then 50mg. The majority of pills prescribed today have less than 50mg of ethinyl oestradiol and two have just 20mg (Loestrin 20 – Parke Davis; Mercilon – Organon). At this level, the oestrogen content is only a little more than that found in hormone replacement therapy (HRT). HRT does not suppress follicular development or ovulation and it therefore follows that the 20mg oestrogen pills will be the minimum effective dose.

Mortality risks are negligible.

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