For most women, conception is possible from their early teens to their mid-40s, and a sexually active woman who doesn't use any method of contraception has an 85% chance of becoming pregnant within one year. Surveys suggest, however, that less than 50% of sexually active women regularly use a reversible method of contraception, while those most keen to avoid pregnancy - teenagers and women over 40 - are least likely to use any form of contraception at all. As a result, around one in three pregnancies are unplanned.
Failure rates of various methods per year
The following table shows typical effectiveness rates for various methods of contraception (allowing for some human error), to help you decide which method is right for you, based on their reliability:
Combined Oral Contraceptive Pill
What it is
The combined oral contraceptive pill is one of the most reliable methods of contraception - if used properly. It contains two synthetic hormones, an oestrogen and a progestogen. It's taken every day for 21 days, and then a seven-day pill-free interval occurs, during which a progestogen withdrawal-bleed (similar to a period) usually occurs. As long as you have taken the pills as prescribed, you're still protected against pregnancy during this seven-day break. Some brands contain seven inactive pills, so you don't have to remember when to restart each pack after your pill-free break. These are known as 'every day (ED) packs'.
How it works
The combined pill prevents pregnancy by:
As long as you remember to take it exactly as prescribed, the combined oral contraceptive pill has a failure rate of less than 1%.
Pros
Cons
Progestogen-only (Mini) Pill
What it is
The progestogen-only pill (POP) contains a single synthetic hormone, a progestogen, in a much lower dose than that contained in the combined pill.
How it works
The POP acts as a contraceptive by:
The progestogen-only pill is usually started on the first day of menstrual bleeding. Contraceptive protection is then achieved within about four hours. It's taken consecutively, every day, without a tablet-free break (even during menstruation), and must be taken within three hours of its due time in order to be effective. The mini pill has a failure rate of less than 1%, when taken regularly, as prescribed. Most pregnancies are the result of forgetting one or more pills, or not taking the pills on time. User error increases the failure rate to an average of about 4%.
Pros
Cons
Injectable Long-acting Progestogen
What it is
The contraceptive injection is a slow-release store (depot) of a synthetic progestogen hormone (medroxyprogesterone acetate). The first injection (into your buttock or arm) is initially given during the first five days of your period (to rule out pregnancy) or within the first five weeks after childbirth. If you're breastfeeding, however, the first injection is delayed until six weeks after delivery. After your first dose, the injection is repeated every 12 weeks, as required.
How it works
The depot progestogen injection works by:
Pros
Cons
Contraceptive Patch (EVRA)
What it is
A hormonal skin patch that's worn for one week at a time, and changed on the same day of the week, for three consecutive weeks. The fourth week, during which a withdrawal bleed occurs, is 'patch-free'. It can be worn on one of four body areas - the buttocks, abdomen, upper torso (excluding the breasts) or upper outer arm.
How it works
The contraceptive patch delivers a continuous flow of hormones (norelgestromin plus ethinyl estradiol) through the skin into the bloodstream. It prevents pregnancy by suppressing ovulation, like the combined pill (see entry). The hormones in the patch also thicken the cervical mucus, making it more difficult for sperm to enter the uterus. When used correctly, it's as effective in preventing pregnancy as combined oral contraceptives (failure rate less than 1%).
Pros
Cons
Male Condom
What it is
Male condoms are made from vulcanised latex rubber, or from polyurethane, which has the advantages of being twice as strong as latex, thinner and non-allergenic.
How it works
Condoms provide a physical barrier to prevent sperm entering the female reproductive tract. Condoms are most effective when used with a spermicidal cream or gel. Apart from protecting against any spilled sperm, this provides extra lubrication, so the condom is less likely to burst than when used dry. It's important to use only a water-based lubricant, as petroleum jelly and mineral oils such as baby oil weaken latex rubber. Condoms also help to protect against sexually transmissible infections.
When used correctly, condoms have a method failure rate of 2% to 5% per year. Typically, however, incorrect use, and the risks of bursting or coming off, increase the typical failure rate to between 11% and 15%.
Pros
Cons
Female Condom
What it is
The female condom is a pre-lubricated, loose-fitting, disposable polyurethane sheath, which fits inside the vagina. It contains two flexible rings, one of which is attached, and remains outside the body. The smaller, inner ring sits loosely inside the sheath, and is used to help insertion. It sits up high in the vagina, and holds the sheath in position, beyond the pubic bone.
How it works
The female condom provides a physical barrier, to prevent sperm entering the female reproductive tract. It also helps to protect against sexually transmissible infections. When used carefully, the failure rate may be as little as 2%, but can be as high as 15% at 12 months.
Pros
Cons
Make the right choice of contraception for you.
Dr Sarah Brewer explains each method
Family planning is an essential part of reproductive health, letting you choose whether to have children, how many to have, and when to have them. The right contraception will help you enjoy your relationship to the full, without the worry of an unplanned pregnancy.
Choose a method:
Method
Typical failure rate
No contraception
85%
Withdrawal
19%
Natural fertility awareness methods
Up to 23%
Fertility awareness computer (Persona)
6% or more
Diaphragm/cap
Up to 18%
Spermicides alone
25%
Male condom
Up to 15%
Female condom
Up to 15%
Coil (IUCD)
1% to 2%
Progestogen coil (intra-uterine system)
< 1%
Combined pill
< 1 - 3% or more
Mini pill
< 1 - 4% or more
Depot progestogen injection
< 1%
Female sterilisation
< 1%
Male sterilisation
< 1%
Emergency contraceptive pill
Up to 4%
Emergency contraceptive IUCD
Up to 2%