Help & Advice


What is birth control?

Birth control refers to any practices, methods, devices, medications or surgical procedures used to reversibly or irreversibly prevent pregnancy from occurring.  They work to inhibit pregnancy in sexually active women by interfering with the normal process of either:

  • Ovulation or the release of a mature egg from an ovary
  • Fertilisation of an egg cell with sperm
  • Implantation of a fertilised egg into the uterus

Other terms used to describe birth control include:

  • Family planning
  • Pregnancy prevention
  • Contraception

Types of birth control include:

Natural methods:

  • Rhythm method - abstaining from sex when ovulation is most likely
  • Coitus interruptus - the deliberate withdrawal of the penis from the vagina just prior to ejaculation

Artificial methods:

  • Barrier methods (such as condoms or diaphragms) - prevent sperm from reaching the egg
  • Hormonal contraceptives - most types inhibit ovulation
  • Intrauterine devices - prevent implantation
  • Spermicides - kill sperm
  • Sterilisation (such as vasectomy or tubal ligation) - require surgery and though sometimes are reversible, should be considered to be permanent

What types of oral contraceptives are available?

Combined hormonal contraceptives (around 99% effective when used correctly):

  • Contain two types of female hormones, an oestrogen and a progestogen
  • Available in various forms of combined oral contraceptive pills (COCP or simply “the pill”), a patch (Evra) and a vaginal ring (NuvaRing)
  • COCP
    • Used by 25% of women in the UK to prevent pregnancy
    • Work by preventing ovulation, thickening the fluid in the cervix to make it more difficult for sperm to enter and altering the lining of the womb to make it more difficult for it to accept an egg
    • Divided into four or five generations based on when they were developed and what progestogen component they contain
    • Risks of cardiovascular problems and venous thromboembolism
    • Potential non-contraceptive benefits are:  treatment of acne, hirsutism, polycystic ovarian syndrome, endometriosis, dysmenorrhea and cycle regulation
    • Examples include:  Loestrin, Microgynon, Ovranette, Rigevidon, Gedarel, Marvelon, Mercilon, Dianette, Yasmin, Qlaira

Progestogen only contraceptives:

  • Progestogen only contraceptive pills (POCPs)
    • Used by 5% of women in the UK
    •  Work in the same way as COCPs.  However, without the oestrogen component, ovulation could still occur.
    • Ideal in those who are breastfeeding or unable to tolerate oestrogen
    • Must be taken around the same time each day because most have a shorter window of effectiveness after a missed dose.
    • Cerazette is the exception with a 12 hour window for a missed dose and 97% prevention of ovulation
    • Irregular periods and breakthrough bleeding could occur
    • Examples include:  Micronor, Noriday and Cerazette
  • Injectable (Depo-Provera and Noristerat)
  • Subdermal implant (Nexplanon)
  • Levonorgestrel-releasing intrauterine system

Why do oral contraceptives sometimes fail?

The common causes of failure are:

  • User failure (most common) - pregnancy occurs due to improper use of a contraceptive
  • Method failure - pregnancy occurs even though the contraceptive was used correctly

In the UK 75% of women aged 16-49 years use some form of contraception.  Although the most popular types are COCPs (25%) and male condoms (25%), there are plenty of methods to choose from to suit every lifestyle.