FFinalistSouthampton · 2027
Obstetrics & gynaecology
AKT · Obstetrics & gynaecology/Contraception

Progestogen-only pill (POP)

Progestogen only — cervical mucus (desogestrel also inhibits ovulation)

Overview

An oestrogen-free pill — the go-to oral method when oestrogen is contraindicated (migraine with aura, breastfeeding, VTE risk, smokers ≥35). Traditional POPs thicken cervical mucus; desogestrel additionally inhibits ovulation. Taken continuously with no break.

Recognise

  • Taken every day with NO pill-free interval
  • Desogestrel: 12-hour late window; traditional (levonorgestrel/norethisterone): only 3 hours
  • Irregular bleeding is the commonest side effect and reason for stopping
  • Very few contraindications (current breast cancer is the main UKMEC 4)

Red flags

  • Current breast cancer (UKMEC 4). A late/missed pill or severe vomiting/diarrhoea → extra precautions

Differentials & how to tell them apart

Combined oral contraceptivecontains oestrogen — better cycle control but contraindicated in migraine-with-aura/VTE/breastfeeding where the POP is safe
Contraceptive implantprogestogen LARC — removes adherence risk, more effective
Depot injectionprogestogen every 13 weeks; BMD concern

Investigations

History (suitable when oestrogen is contraindicated); exclude pregnancy. No routine BP requirement as there is no oestrogen.

Management

Progestogen-only pill when oestrogen is contraindicated (e.g. migraine with aura, breastfeeding)

  1. 1Choose when oestrogen is contraindicated or unwanted. Start; if not days 1–5, use 2 days extra precautions (desogestrel/traditional differ).Gate: Desogestrel allows a 12-hour late window; traditional POPs only 3 hours — beyond it, extra precautions for 2 days
  2. 2Persistent troublesome bleeding → reassess, consider alternative method.
Desogestrel — inhibits ovulation; 12-hour missed-pill window
Levonorgestrel/norethisterone (traditional) — mucus effect; strict 3-hour window

Key points

The safe oral choice in the COCP UKMEC 4 scenarios. Breastfeeding: POP can be used from birth.

Monitor & prognosis

Bleeding pattern; adherence/timing.

Rapidly reversible.

Source: FSRH UKMEC 2016; FSRH POP guidance