Oral contraception


Hormonal contraception is a pharmacological method to inhibit normal reproductive function and to prevent fertility. The steroid contraceptives (estrogens and progestagens) prevent ovulation by their negative feedback on hypothalamic LHRH secretion and pituitary LH/FSH secretion. Progestagens alone inhibit the LH peak. Besides prevention of the LH surge, they also make the female reproductive tract inhospitable for implantation of a fertilized egg. Estrogens are added to OAC to prevent spotting.

In the Netherlands various kinds of hormonal contraceptives are on the market of which the oral contraceptives (OAC) are the most important. First choice for contraception is a combination of an estrogen and a progestagen with less than 50 μg of the estrogen (sub-50 pill) of the so-called second generation with one phase (all pills have the same composition). These drugs are highly effective, have a low risk for thrombosis, are cheap, and are easy in use. Known examples are pills containing an estrogen and a progestagen. Estrogens are added to OAC to prevent spotting (breakthrough bleeding). The estrogen component in the pill is balance: >30 μg increases the risk for thrombosis, <30 μg increases the chance for spotting.


Recently, new forms of hormonal contraception have become popular such as the vaginal ring with estrogen and progestagen (3rd generation), implants with progestagen, and injectables with progesterone. Intra-uterine devices (IUDs) containing copper or a progestagen exist as well, but need insertion by a physician.

Minor side effects of oral contraception such as weight gain, headache, tensed breasts and glucose intolerance can cause women to stop OAC. Women with hypertension have a higher risk for arterial thrombosis when using OAC. Research under pill-users revealed a significant larger risk of mamma carcinoma compared to non-users. There is a relation with early use of OAC (just after menarche when the cycle is still irregular) and the development of mamma carcinoma. Furthermore, oral contraceptives can influence serum lipid concentrations.

Due to interactions with drugs that alter activities of liver P450 enzymes, oral contraceptives can have decreased reliability. These interactions are shown with some anti-epileptics and certain antibiotics (tetracyclines, penicillines, and rifampicine).


A patient who has just started using an OAC comes back to her doctor complaining of a side effect. Which side effect will she most probably complain about? 


Your patient is taking tetracycline and oral contraceptives.


Contraindications to oral contraceptive therapy include: