oral contraceptive pill
Meaning of oral contraceptive pill: A daily hormone tablet that prevents pregnancy chiefly by keeping the ovary from releasing an egg at all.
Definition of oral contraceptive pill
An oral contraceptive pill is a tablet taken by mouth to prevent pregnancy, using hormones that stop the ovaries from releasing an egg. Combined pills contain both an estrogen and a progestin, while progestin-only pills contain the second hormone alone. Both also thicken the mucus at the neck of the womb and thin its lining, adding further barriers to conception.
How does it prevent pregnancy?
The brain normally controls the ovary by releasing hormones in a rising and falling monthly pattern. A steady daily dose of estrogen and progestin flattens that pattern out. Without the mid-cycle surge that normally triggers release of an egg, ovulation does not occur. Two backup effects work alongside that. The mucus at the cervix becomes thick and difficult for sperm to cross, and the lining of the womb stays thin. Protection depends on the hormone level staying continuous, which is why the timing of each dose matters more for some formulations than for others.
What are the main types?
| Type | Contains | Notes |
|---|---|---|
| Combined pill | Estrogen and progestin | The commonest form, taken in cycles |
| Progestin-only pill | Progestin alone | An option when estrogen is unsuitable |
| Extended or continuous | Combined hormones | Fewer or no withdrawal bleeds |
What else are these tablets used for?
Contraception is the main purpose, but the same medicines are prescribed for heavy or painful periods, irregular cycles, acne, and the pain of endometriosis, a condition in which womb-like tissue grows outside the uterus. Long use of combined pills is associated with a reduced risk of cancer of the ovary and of the womb lining, an effect that persists for years after stopping.
What risks come with them?
The estrogen component raises the chance of a clot forming in a leg vein or the lung. The absolute risk stays small in healthy non-smokers and climbs with smoking, older age, obesity and migraine that begins with visual warning signs. Pregnancy itself carries a higher clot risk than the pill does, which is part of how that risk is weighed. Breast cancer risk is slightly raised during use and falls back toward the background level after stopping. Irregular bleeding, breast tenderness and nausea are common in the early months and often settle.
Also known as
Used in a sentence
The history recorded ten years of oral contraceptive pill use with no reported complications.
Good to know
Combined pills carry a small rise in the risk of blood clots that increases with smoking and age, while progestin-only pills leave out the estrogen responsible for it.