Contraceptive Pill Types Explained

This is an introductory explanation of the different types of oral contraceptive pills that may help you to finally select the one that is best for your body. 50 years on, we have discovered that the oral contraceptive pill for women still prevents pregnancy if it is made up of much lower doses of estrogen and progestin than in the early days. 'The Pill' used to contain 50-100 micrograms of estrogen and today it contains only 20-35 micrograms, with researchers trying to reduce this amount further to reduce side effects. Synthetic hormones (estrogen/ethinyl estradiol and progestin) used in contraceptive pills mimic the natural hormones (oestrogen and progesterone) produced by the ovaries, adrenal gland and liver.


Estrogen's main job in the contraceptive pill is to prevent ovulation (release of an egg from a woman's ovary). Progestin in the pill, while it does have some intermittent effect on ovulation (about 50% of the time) is relied on mainly to thicken the mucus around the cervix to stop sperm from getting through to an egg.

Contraceptive Pills come in two basic types: single hormone pills (progestin only) and combination hormone pills (estrogen + progestin) Pills are supplied in two basic packs- 28 day pill packs= 3 weeks of active hormone pills +1 week placebo pills and 21 day pill packs= 3 weeks of active hormone pills with no placebo pills.

PROGESTIN only pills (the 'mini pill') do not contain estrogen and only have a small amount of progestin in them. Breastfeeding women are often prescribed these 'mini pills' (estrogen may cause a reduction in milk supply) as well as women who cannot take synthetic estrogen for medical reasons. Side effects are less than pills containing estrogen and they are not associated with heart disease, however, irregular bleeding /spotting/mood swings may occur. Progestin only pills MUST be taken at the same time each day and are affected by vomiting or diarrhoea.This type of contraceptive pill is not affected by antibiotics.

COMBINATION PILLS- contain estrogen and progestin and can be further categorized as being Monophasic, Biphasic or Triphasic- so what do these terms mean? Pills are put into these categories according to whether or not the levels of hormones they contain stay the same throughout the first three weeks of a woman's menstrual cycle (in 28 day pill packs, the pills for the fourth week in the pack are placebo or 'reminder pills' that are inactive and do not contain any hormones)

MONOPHASIC Pill- is one that contains the same amount of hormones in every ACTIVE pill so you are less likely to have mood swings as your hormone levels do not vary much throughout the month. Popular monophasic pills include:Alesse, Brevicon, Desogen, Levlen, Levlite, Loestrin, Modicon, Nelova, Nordette, Norinyl,Ortho-Cept, Ortho-Cyclen, Ortho-Novum, Ovcon, Yasmin. In 2003 the FDA approved a new packaging of a monophasic contraceptive pill called Seasonale. This pill is taken for 91 days, during which no periods occur -so in one year, women taking this pill will only have 4 periods (for the first year though, expect the same no. of menstrual days as with a traditional contraceptive pill till your body adjusts)

BIPHASIC Pill- is one that contains different amounts of hormones throughout the pack. These pills alter your hormone levels once during your cycle by increasing the dosage of progestin about halfway through your cycle and are thought to better match your body's natural production of hormones- they contain smaller doses of hormones in total than monophasic pills. However, insufficient evidence has been gathered to favour these pills over monophasic ones, where much more reliable data is available so monphasic pills are preferred. Breakthrough bleeding has been reported as a side effect with these pills. Popular biphasic pills include : Jenest, Mircette, Necon 10/11, Nelova 10/11, Ortho-Novum 10/11. Attempts to decrease side effects led to the three-phase pill in the 1980s.

TRIPHASE Pill- is one that contains 3 different amounts of hormones in the ACTIVE pills over three weeks, i.e. a change in hormone levels within the body occurs every 7 days for the first 3 weeks.. The dose of estrogen is gradually increased and in some pills, the dose of progestin is also increased. Whether three-phase pills lead to fewer pregnancies than two-phase pills is unknown. Nor is it known if the pills give better cycle control or have fewer side effects. Look for the 'TRI' on the label such as:Ortho Tri-Cyclen, Triphasil, Tri-Levlen, Trivora, Tri-Norinyl, Cyclessa, Ortho-Novum 7/7/7.

The Best Pill to Take? All contraceptive pills are effective if taken correctly, with combination pills (containing estrogen and progestin) being more effective than the low dose 'mini pill'. Monophasic pills may be the best to start with- they are cheaper and those with lower amounts of estrogen may have fewer side effects (but more breakthrough bleeding)

Always use back up (a condom or diaphragm) for the rest of the month if you miss a pill. Trial and error, side effects and talking to your doctor should help you to find a contraceptive pill that suits your body. Pregnancies occur mainly when women forget to take a pill or take them incorrectly, vomit, get diarrhoea or, in the case of the mini pill, do not take pills at the same time each day. It is very easy to start a pill packet late if you just forget or if you don't have the next new packet on hand. The most dangerous time to miss a pill is at the end or beginning of a packet because it lengthens the pill free interval beyond seven days which means that you may not have absorbed sufficient synthetic hormones to prevent you from ovulating in the next month.