Contraception: injection, implant or skin patch of slow release progesterone to inhibit the maturation and release of eggs for a number of months or years

The idea

This method delivers progesterone slowly from an injection, an implant placed under the skin, or a skin patch. The progesterone enters the blood at a steady rate, so its concentration stays high for months or years without a daily pill. The high progesterone level acts on the pituitary gland and reduces the release of FSH and LH. Less FSH means follicles do not develop and eggs do not mature; less LH means a mature egg is not released from the ovary. The progesterone also thickens cervical mucus and thins the uterus lining, which makes fertilisation and implantation less likely. Because the dose is slow release, the contraceptive effect lasts for a set period, such as several months for an injection or several years for an implant, after which it must be replaced.

What earns the marks

• Progesterone is delivered by injection, implant or skin patch rather than by a daily oral dose.
• The delivery system releases progesterone slowly, keeping a steady level in the blood for months or years.
• The raised progesterone level reduces the release of FSH and LH from the pituitary gland.
• Reduced FSH means eggs do not mature, and reduced LH means no egg is released from the ovary.
• The method is assessed by linking the slow-release route to a long-lasting contraceptive effect.
• Progesterone also thickens cervical mucus and thins the uterus lining, adding to the contraceptive effect.

Common mistakes and how to put them right

• Saying the implant or injection contains FSH.

  Put it right: It releases progesterone, which reduces FSH and LH release.

• Confusing the duration of each method.

  Put it right: An injection usually lasts a few months, while an implant can last several years, and the patch is changed on a regular schedule.

• Writing that progesterone directly blocks the fallopian tube.

  Put it right: It acts mainly through the pituitary gland to reduce FSH and LH, preventing egg maturation and release.

Exam tips

• Name the route of delivery and state that it is slow release, then link this to the long duration of effect.
• Use the phrase 'inhibits the maturation and release of eggs' and explain it through reduced FSH and LH.
• When comparing with oral contraceptives, mention that the slow-release method does not require taking a pill every day.