Female Hormonal Methods Of Contraception

Female Hormonal Methods Of Contraception

One of the most popular forms of birth control is the contraceptive Pill. Oral contraception uses controlled doses of artificial hormones given by mouth to act on the woman’s body.

A combined Pill is made up of oestrogen and progesterone, and these prevent the ovaries from releasing an egg each month. In effect, the body ‘believes’ and acts as if it were already pregnant. A Pill is taken once every 24 hours, for about three weeks. At the end of this time the woman has one week without Pills, before beginning a new packet and repeating the cycle. During this week, the withdrawal from the hormone treatment will trigger bleeding. This resembles menstrual bleeding. However, the action of the hormones during the three weeks of Pill taking, will mean the lining of the womb is thinner than normal, and so periods on the Pill are usually scantier and shorter than usual. Many women find they experience breakthrough bleeding* midway through their first packet of oral contraception, as their bodies adjust to the regime. This could signal that a higher dose of oestrogen is necessary. It is the oestrogen component of the Pill that causes most of the adverse effects, which is why doctors prefer to prescribe the lowest possible dose, and find the majority of women settle on 30 mcg of oestrogen.

The combined Pill mentioned above contains the same proportion of oestrogen to progesterone in each pill; the triphasic or biphasic Pill also contains both oestrogen and progesterone and is taken for 21 days of the cycle. In an attempt to mimic natural fluctuating levels of hormones, these are combined Pills with two or three different proportions of hormones to be taken in varying amounts. The difference to the user is that while consecutive packets of other combined Pills may be taken to avoid a period, this cannot be done with the biphasic or triphasic types. As the pills vary in composition, they must be taken in the correct sequence in order for them to work. It is possible that breakthrough bleeding and ovulation may occur.

The progesterone-only or ‘mini’ Pill does not contain any oestrogen. This has the advantage of eliminating the side-effects such as nausea, breast discomfort, or spotting of blood between periods, which can bother some women on the combined Pill, which are mainly caused by the oestrogen. The progesterone-only Pill does not prevent ovulation. It works by thickening the cervical mucus to block the sperm from the uterus, slowing down the action of the cilia in the Fallopian tubes which in turn slows down the passage of the egg towards any vigorous sperm, and making the womb lining hostile so that if an egg is fertilized, it is unlikely to implant. The mini Pill is taken every day, without a break. Menstrual periods should arrive as normal although some women find that their periods become erratic or stop altogether.

Whereas the combined Pill is practically 100 per cent safe if taken properly and no pills are lost through vomiting or diarrhoea, the mini Pill is slightly less reliable with a failure rate of about two per cent. The combined Pill has a safety margin of several hours, and maintains protection as long as it is taken within 36 hours of the last dose, each mini Pill must, however, be taken within 26 hours of the last. With both the combined and the progesterone-only Pills fertility usually returns as soon as they are stopped. However, some women find their periods and fertility take a few months to settle down.

The combined Pill has probably been under more medical scrutiny than any other medication in history. There are both realistic and unfounded fears about its safety. It does appear to increase an already present tendency to high blood pressure and blood clots, which could cause strokes or heart attacks and being over 35, overweight or a smoker also increases any such risks.

Combined hormonal tablets can also be used as an emergency contraceptive, the so-called ‘morning-after Pill’. It was discovered that a high dose of oestrogen, taken within 72 hours of unprotected intercourse and repeated on the following four days, has the effect of preventing implantation. Formerly the total dose of oestrogen needed to accomplish this was about 25mg (about 1,000 times as much as the oestrogen content of one normal Pill). This prevented pregnancy in 99 per cent of the cases, by providing an inadequate uterus lining for the fertilized egg. However such large doses cause serious nausea. Nowadays different chemicals are used that also prevent the building of a nourishing uterus lining. They have the advantage that nausea is less likely to develop and that they can be taken longer after an unprotected intercourse has occurred. They may even be used to induce menstruation.

All the above methods however are only emergency measures and not a regular method of birth control. Another way of introducing hormones into the woman’s system is by injection. A depot injection of progesterone is given that can prevent pregnancy for three months. However, while being a boon to those who find it difficult to use other methods, it does have its drawbacks. Women can find their periods become erratic, breakthrough bleeding may occur and some put on weight. Moreover, once it is given, treatment cannot be stopped and any side-effects could therefore be present for some time.


In the Western world breastfeeding is not an effective method of birth control. It only seems to be so in countries where babies are carried slung across bared breasts and are allowed to feed almost continuously. This produces constant stimulation of the woman’s hormonal system which is required to stop ovulation and thus conception.