15th April 2024

Contraception

The term contraception encompasses a variety of methods to prevent pregnancy and manage irregular menstruation. These can be split into hormonal and non-hormonal methods. The UK Medical Eligibility Criteria for Contraceptive Use (UKMEC) outlines guidance on starting contraception. There are four stages ranging from UKMEC 1 (no restrictions) to 4 (absolute contraindication). The below will explain certain relevant methods of contraception.

Combined oral contraceptive pill

The COCP has both oestrogen and progestogen. Absolute contraindications include a history of migraines with aura due to stroke risk, a history of thromboembolic disease or stroke, current breast cancer and if the person is >35 years of age while smoking >15/day. The COCP has been associated with cholestasis and certain dermatological conditions, including erythema nodosum, Stevens-Johnson syndrome, erythema multiforme, acanthosis nigricans and alopecia.

Progesterone only pill

The progesterone-only pill (POP) is slightly less effective compared to other oral contraceptives but can be used as an alternative when the COCP is contraindicated. It does not carry the risk of thromboembolism and does not affect lactation (thus can be used during breastfeeding).

Intrauterine devices and intrauterine system

Intrauterine devices (IUDs) are inserted into the endometrium with active forms containing copper-inhibiting implantation enzymes. These are typically replaced every 5 years and can be used as emergency contraception. As it does not use hormones, there are no hormonal side effects.

The intrauterine system (IUS) is inserted into the uterine cavity and contains progestogen, which prevents endometrial proliferation, suppresses ovulation and thickens cervical mucus. With both the IUD and IUS, there is an increased risk of pelvic infections and ectopic pregnancy.

Progesterone implant 

The progesterone implant is a long-term contraceptive device which slowly releases hormones that prevent ovulation. In addition to this, it thickens cervical mucosa and thins the endometrium. It lasts for 3 years. This method is contraindicated in severe LFT derangement, acute porphyria and previous breast cancer.

References

• Adam Feather, David Randall, Mona Waterhouse, Kumar and Clark’s Clinical Medicine: (10th edition), ed. by John Booth, Kate Wiles, 10th edn (Elsevier, 19 June 2020).
• Mary Lowth, Progestogen-only Subdermal Implants (2019) <https://patient.info/doctor/progestogen-only-subdermal-implants#nav-1>