Benefits of low dose oral contraceptives

By DR S P Moodley MBChB (Natal), FRCOG (London), FCOG (SA), FECSM Specialist Obstetrician & Gynaecologist Ethekweni Hospital & Heart Centre Umhlanga Hospital & Victoria Hospital (Tongaat) Executive Committee Member of SAMS (South African Menopause Society) Chairperson KZN branch of SASHA (South African Sexual Health Association) KwaZulu-Natal

The main aim of contraception is to empower an individual female or couple to plan their lives. Contraception must effectively prevent pregnancy and simultaneously not interfere with sexuality. It falls into the realm of preventive medicine; therefore, even more attention must be paid to any possible side effects.

Hormone contraception was first approved for use in the USA in 1960. A hormone is a chemical substance that can inhibit or stimulate function in a target organ. A combined pill has two hormones, estrogen and progesterone. The commonest estrogen in the combined pill is ethinyl estradiol. The principal factor influencing estrogenic side effects is related to the dosage of the ethinyl estradiol in the combined pill.

The progestogenic side effects are related more to the type of progestogen in the combined pill. The main mechanism of action of the combined pill is to suppress ovulation. It achieves this by decreasing gonadotrophin secretion, thereby suppressing estrogen and progesterone secretion by the ovaries. The lack of estrogen positive feedback prevents the mid-cycle LH surge which is a pre-requisite for triggering ovulation. The progesterone component decreases the amount and thickens cervical mucous, thus providing a hostile environment for sperm capacitation. Progestens also slow tubal motility and causes endometrial atrophy. The latter would negatively impact implantation.


The frequently mentioned side-effects of the combined pill such as nausea, vomiting, increases in blood pressure and melasma are not strongly associated with low dose formulations such as Minesse (a low dose estrogen progesterone combination). The only downside to the low dose oral contraceptives is breakthrough bleeding and it requires more accurate timing of pill ingestion.

Minesse has 15 ugs of ethinyl estradiol and 60 ugs of gestodene. There are only 4 placebo pills in Minesse (as opposed to the conventional 7). This facilitates better ovulation inhibition and shorter menstrual bleeds.

In counselling patients, one must not forget the possible non-contraceptive indications for the combined pill such as polycystic ovarian syndrome, dysmenorrhoea, endometriosis, menorrhagia, amenorrhoea, irregular menses, acne and premenstrual syndrome. It is also easy to delay menses if desired by skipping the placebo pills. A classic example of the latter is in patients with endometriosis and dysmenorrhoea where three to four bleeds a year are engineered.

The public perception of weight gain with the use of the combined pill is inaccurate and promotes poor compliance.

In discussing the effectiveness of combined oral contraceptives, one must distinguish between perfect use which will give the method failure rate versus actual or typical use. The latter is influenced by the accuracy of the advice given and empathy of the caregiver. There can also be mistakes on the part of the consumer; sometimes this may be conscious non-use. It is also important to advise that the combined pill is only effective after 2 weeks of use. Other reasons for decreased efficacy are intestinal malabsorption (vomiting and diarrhoea) and drug interactions. Common drugs to be aware of include Rifampicin, antiepileptics and broad-spectrum antibiotics. Breakthrough bleeding may be an indication of decreased efficacy.

The public perception of weight gain with the use of the combined pill is inaccurate and promotes poor compliance. Patients should always be advised that weight gain tends to increase with age and pregnancy. The rare patient who experiences rapid weight gain (within months of use) often implies fluid retention, should be offered an alternative method.

Thrombo-embolism is relatively rare with the second generation oral contraceptives (15 per 100000 users per year versus 5 in non-users and 60 per 100000 pregnancies per year). There have been increased reports of thrombo-embolism in pills containing the third generation progestogens such as Drosperinone, Gestodene and Desorgesterol (25 per 100000 users per year).

Long term users of the combined oral contraceptive pill may experience a reduction in libido. This is related to the increase in Sex Hormone Binding Globulin which decreases the bioavailable testosterone. This is a class side effect and is related mainly to the estrogen component of the combined pill. Theanti-androgenic action of certain classes of progesterone may contribute, e.g. drosperinone and cyproterone acetate. The care giver must be cognisant of the fact that female sexual dysfunction often has a multifactorial aetiology.


Contraindications to the use of the combined pill include: pre existing cardiovascular diseases, familial history of thrombosis, severe obesity, liver diseases, smokers over the age of 35 years, known or suspected breast cancer, hypercholesterolemia and headaches, especially if it develops while on the pill. The low dose combined oral contraceptives have expanded the choices available to women. Every medical intervention will have benefits and disadvantages and the patient or client must be part of the decision making. The emancipation of women is related to education. The pill revolutionized family planning. Women could make this decision privately as pill use was not directly related to the act of coitus. It allowed women to prolong the age of marriage or child bearing, thus affording her better opportunities for education and career advancement. It also heightened the debate about the moral consequences of pre-marital sex and promiscuity. Obviously a balance has to be found, but hopefully this should be based on a legitimate informed choice. References on request.