Progestogen-Only Contraception

Options: progestogen-only pill (POP), etonogestrel implant, levonorgestrel IUD (Mirena/Kyleena), depot medroxyprogesterone (DMPA). All are suitable when oestrogen is contraindicated and safe while breastfeeding.

Progestogen-only pill (POP)

Agent	Brand
Levonorgestrel 30microg	Microlut
Norethisterone 350microg	Micronor, Noriday 28
Drospirenone (24/4 regimen)	Slinda

Traditional (levonorgestrel/norethisterone) POPs rely on cervical mucus changes and don’t reliably suppress ovulation — efficacy is lost with even a few hours’ delay (traditional POPs: >3hrs late needs 48hrs of barrier contraception). Drospirenone POP (Slinda) is an exception — it has a 48hr missed-pill window, the same interval as a combined oral contraceptive, which can be more convenient for timing adherence (see Combined Hormonal Contraception).

Side effects: irregular/unpredictable bleeding, occasional amenorrhoea, may worsen acne.

Etonogestrel implant (Implanon NXT)

Extremely effective (99.95%), long-acting (3 years), minimal user involvement, first-line at any age including adolescence (no adverse BMD effect), safe immediately postpartum/ while breastfeeding.

Insertion (subdermal, radio-opaque Implanon NXT): non-dominant arm, over the triceps away from the sulcus (eTG landmark; consistent with the classic “8–10 cm from the medial epicondyle”). Mark the insertion point and a target point ~4 cm along; anaesthetise; insert with the applicator; palpate immediately afterwards to confirm placement (X-ray can confirm if in doubt — it is radio-opaque).

Removal: check the user card for location; palpate to confirm the site; antiseptic; local anaesthetic around and below the distal tip (so the local doesn’t push it deeper); press on the proximal tip to make the distal tip lift the skin; make a ~2 mm incision, grasp with forceps and withdraw; confirm the full 4 cm has been removed by measuring it.

Contraindications: the only UKMEC 4 contraindication is current breast cancer. UKMEC 3 (expert judgement): unexplained vaginal bleeding pending investigation, past breast cancer, severe cirrhosis, hepatocellular adenoma/malignant liver tumour, or new ischaemic heart disease/stroke/TIA developing during use. Safe (UKMEC 2) in those with a past history of IHD, cerebrovascular disease or VTE — a materially more permissive framework than the historical view of progestogen-only methods and VTE risk.

Bleeding: amenorrhoea in ~20%, frequent bleeding in 7%, prolonged bleeding in 18% — often settles over the first 3 months as serum etonogestrel drops. If bleeding remains troublesome and continuation is desired, evidence-based add-on options: a combined hormonal contraceptive (continuous or cyclical, up to 3 months), a 5-day NSAID course, or tranexamic acid if heavy. Weaker-evidence options: oral norethisterone, twice-daily levonorgestrel POP for 20 days, or implant replacement.

Deep/impalpable implant: if not palpable at any point, it must still be located — arrange an X-ray to confirm presence, then refer for ultrasound-guided specialist removal; use additional contraception until located. Extremely rare cases of migration to the pulmonary vasculature have been reported — if imaging doesn’t find it, the manufacturer can advise on chest imaging or arrange serum etonogestrel testing.

Depot medroxyprogesterone (DMPA)

150mg deep IM every 12 weeks (±2 weeks). Immediately effective days 1–5 of cycle, <21 days postpartum, ≤5 days post-abortion, or switching from implant/copper IUD (days 1–5); otherwise takes 7 days.

Contraindications: the only UKMEC 4 is current breast cancer. UKMEC 3: unexplained vaginal bleeding pending work-up, past breast cancer, severe cirrhosis, hepatocellular adenoma/liver tumour, multiple cardiovascular risk factors, hypertension with vascular disease, or history of IHD/stroke/TIA. Unlike other progestogen-only methods, DMPA carries a theoretical (unproven) cardiovascular risk via an adverse lipid effect — multiple CV risk factors or CV history warrant specialist input.

Bone density: not a UKMEC criterion, but caution is advised in those <18yrs (not yet at peak bone mass) or >45yrs (approaching menopause) — consider DXA if other osteoporosis risk factors are present. Assess BMD and cardiovascular risk factors annually in ongoing users.

Stopping: recommend switching to another method by age 50 — harms outweigh benefits at that age. Return of fertility is delayed (median 6 months to ovulation, ~95% by 12 months, up to 18 months in some) — don’t investigate amenorrhoea before 12 months post-injection unless another cause (PCOS, galactorrhoea) is suspected or the patient wants to conceive sooner.

Bleeding management: same evidence-based ladder as the implant (add CHC/NSAID/ tranexamic acid; weaker evidence for norethisterone or POP add-on). 50–70% amenorrhoeic by 1 year.

Levonorgestrel IUD (Mirena / Kyleena)

	Mirena (52mg)	Kyleena (19.5mg)
Daily dose (avg. over 5yrs)	14microg	9microg
Replacement interval (contraception)	Every 8 years (extended from 5 in 2024)	Every 5 years
Frame/insertion tube	Larger (32×32mm / 4.4mm tube)	Smaller (28×30mm / 3.8mm tube)
Bleeding	More likely amenorrhoea/infrequent bleeding	More likely irregular bleeding
Non-contraceptive indications	Heavy menstrual bleeding; endometrial protection on MHT (5 yearly regardless of insertion age)	None registered
Endometriosis	Effective	Not studied
Ovarian cyst incidence by 3yrs	22%	8.6%

Contraindications — as for copper IUD below, plus: current breast cancer (UKMEC 4); past breast cancer, severe cirrhosis, liver tumour, or new IHD/stroke/TIA during use (UKMEC 3). Safe (UKMEC 2) with past IHD, cerebrovascular disease or VTE.

Extended use: the 52mg device inserted at ≥45yrs can remain until menopause is diagnosed, or age 55, without replacement — a significant simplification for perimenopausal patients. The 19.5mg device has no such extension and must be replaced every 5 years regardless of age.

Copper IUD

Non-hormonal; works by inhibiting sperm migration/ovum survival/implantation. Immediately effective at any time — the only contraceptive suitable as emergency contraception (inserted within 5 days of unprotected sex, or within 5 days of estimated ovulation), 99%+ effective in that role.

Contraindicated (all IUD types, UKMEC 4): current PID, symptomatic chlamydia/ gonorrhoea/M. genitalium, unexplained vaginal bleeding pending work-up, gestational trophoblastic disease with persistent hCG elevation or malignancy, cervical or endometrial cancer awaiting treatment.

UKMEC 3: asymptomatic chlamydia (can treat on day of insertion), distorted uterine cavity, long QT syndrome (insert in hospital — bradycardia risk), 48hrs–4 weeks postpartum, HIV with CD4 <200, or any condition where a vasovagal response is a concern.

Starting/inserting an IUD (either type)

• Pregnancy must be excluded first (not suitable for Quick Start) — criteria: no sex since last period, consistent effective contraception, within 5 days of period onset, <21 days postpartum, ≤5 days post-abortion, or a negative pregnancy test with no unprotected sex in the last 21 days.
• STI screening (chlamydia/gonorrhoea) recommended for all <30yrs and older patients at risk, to avoid seeding the upper genital tract at insertion.
• No antibiotic prophylaxis is needed — including for patients at risk of infective endocarditis — though abnormal discharge/pain/bleeding should be actively excluded first in that group.
• Observe 15–20 minutes post-insertion for a delayed vasovagal reaction.

Complications

• Uterine perforation: ~0.2% of insertions; risk up to 6-fold higher while breastfeeding, and elevated for the first 9 months postpartum regardless.
• Expulsion: ~5% of IUDs; if reinserting, check for cavity distortion first — a second IUD has a higher expulsion risk than the first.
• Ectopic pregnancy: an IUD failure is much more likely to be ectopic than a pregnancy with no contraception — ~50% of LNG-IUD failures and up to 18% of copper IUD failures are ectopic. Always consider ectopic pregnancy if a patient with an IUD in situ has a positive pregnancy test.
• PID: only attributable to the IUD itself in the first 20 days post-insertion; later infection should be treated as STI-related PID, not procedure-related. The device does not need removal unless infection is severe or not improving within 48–72hrs of antibiotics.
• Missing/altered threads: explore the cervical canal first; if not found, urine pregnancy test + interim contraception + ultrasound to locate the device, escalating to X-ray if not seen on ultrasound (to distinguish expulsion from perforation).