Contraceptive Methods, Bleeding Patterns
1. Normal Menstrual Physiology – the “benchmark”
| Phase | Dominant hormone | Endometrial change | What triggers bleeding? |
|---|---|---|---|
| Follicular | Rising oestrogen | Proliferation of functional layer | |
| Luteal | Progesterone (post-ovulation) | Stabilises & differentiates lining | |
| Withdrawal (menses) | ↓ Oestrogen and progesterone | Vasoconstriction → ischaemia → shedding | Abrupt hormone fall triggers spiral arteriole spasm and tissue breakdown |
Key concept: Any contraceptive that thins the endometrium, removes cyclical hormone withdrawal, or suppresses ovulation will disrupt/abolish a true period.
2. Bleeding Patterns by Contraceptive Class
Class-by-Class Mechanism → Typical Bleeding Pattern
| Class (PBS examples) | Key mechanism(s) | Endometrial & ovarian effect | Resulting bleeding pattern | Why “random” bleeding occurs |
|---|---|---|---|---|
| Combined hormonal contraception (CHC) COCP, NuvaRing®, transdermal patch | • Steady systemic oestrogen + progestin • Cyclic 4–7 d hormone-free interval (HFI) | • Endometrium proliferates under oestrogen • Predictable withdrawal during HFI | Predictable withdrawal bleed (pill period). Can be skipped if HFI omitted. | Missed pills ↓ hormone level mid-pack → unplanned withdrawal → break-through bleeding (BTB). |
| Traditional progestogen-only pill (POP) LNG 30 µg, NET 350 µg | • Cervical mucus thickening • Inconsistent ovulation blockade (<60 %) | • Low, fluctuating progestin; oestrogen rises if ovulation occurs • Lining remains thin but unstable | Unpredictable spotting / prolonged light bleeds | Small day-to-day hormone dips (late pill, diarrhoea) let oestrogen act briefly, then progestin re-atrophies lining → micro-shedding. |
| Desogestrel / drospirenone POP (e.g. Slinda®) | >95 % ovulation suppression | Higher, steadier progestin → greater atrophy | Irregular bleeding early, then ~20 % amenorrhoea | Initial adaption fragility; eventually very thin, vessel-poor lining. |
| Etonogestrel implant Implanon NXT® | • ≥99 % ovulation block • Continuous systemic progestin | • Profound oestrogen suppression but not zero • Atrophic, capillary-rich surface | One-fifth amenorrhoea; one-fifth frequent/prolonged bleeds; rest light/infrequent | Thin, poorly organised surface easily disrupted by minor hormonal fluctuations or mechanical shear. |
| Depot medroxy-progesterone acetate (DMPA) | • 100 % ovulation suppression • Hypo-oestrogenism | • Severe endometrial atrophy over months | Early irregular bleeds → by 12 m ≈ 50 % amenorrhoea; 24 m > 70 % | Takes months to “shut down” lining; until then, fragile tissue sloughs unpredictably. |
| Levonorgestrel IUD Mirena® 52 mg, Kyleena® 19.5 mg | • High local LNG, low systemic • Ovulation continues in many cycles only ~15–45 % cycles anovulatory | • Local progesterone > 20× serum → glands collapse, stroma decidualises; vessels constrict | Scant spotting 3–6 m → amenorrhoea in 12–30 % (dose-dependent) | Early months: newly thinned surface fragile. Later: too little tissue to bleed. |
| Copper IUD | • No hormones • Copper ions inflammatory to sperm/ova | • Normal ovarian cycling • Endometrium inflamed, vascular | Regular timing but ~50 % heavier & crampier | Intact oestrogen-progesterone cycle builds lining; sterile inflammation ↑ angiogenesis & fibrinolysis → heavier loss. |
| Barrier methods / sterilisation | Mechanical / surgical | No endocrine change | Native menses unchanged | Any irregular bleeding → investigate as usual. |
Why do LNG-IUDs often abolish periods?
- Direct endometrial action: Continuous high progesterone at the tissue level → glandular atrophy, decidualised stroma, fibrotic arterioles.
- Oestrogen still rises (ovulation often continues) but the atrophic lining cannot rebuild.
- Result = little or no tissue to shed → light or absent bleeding.
3. Mechanistic Comparison – why some progestogen-only options still bleed
| Factor | LNG-IUD | Implant | POP | DMPA |
|---|---|---|---|---|
| Delivery | Local intra-uterine | Systemic | Systemic oral | Systemic IM |
| Progestin level in endometrium | Very high | Moderate | Low/variable | Moderate–high |
| Oestrogen level | Normal (ovulation continues) | Low-normal | Normal | Low |
| Endometrial state | Marked atrophy → stable | Thin but fragile | Thin + unstable | Profound atrophy (time-dependent) |
| Result | Amenorrhoea / scant spotting | Unpredictable spotting | Unpredictable spotting | Irregular bleeds then amenorrhoea |
4. Practical Management of Contraception-Related Bleeding
4.1 Initial GP checklist
- Confirm correct use: missed pills, delayed injection, IUD strings length, implant age.
- Exclude red-flags: pregnancy, chlamydia, cervical pathology, anaemia.
- Document: timing, quantity (pads/day), triggers, Hb/ferritin.
4.2 Timeline approach
| Time since starting/changing | Action |
|---|---|
| < 3–6 mths | Reassure; provide expected trajectory; offer symptomatic treatment. |
| > 6 mths OR sudden change after stability | Investigate: pelvic USS ± endometrial biopsy (age ≥ 45 y, risk factors). |
4.3 Symptomatic short-course options
| Scenario | Medication & dose | Notes |
|---|---|---|
| Heavy/prolonged bleeding (implant, POP, DMPA, Cu-IUD) | • Mefenamic acid 500 mg TDS OR • Tranexamic acid 1 g TDS × 5 days | Avoid tranexamic if VTE risk. |
| Persistent spotting – progestin LARC | • MPA 10 mg TDS × 5 d OR • COCP (≥ 30 µg EE) × 20 d | Provide CHC cover if using COCP. |
| DMPA troublesome flow | Bring next dose forward to 10 weeks | Improves amenorrhoea rates. |
| COCP BTB after cycle 3 | • Increase EE to 30–35 µg • Change progestin • Consider continuous regimen | Check perfect adherence first. |
4.4 When to switch method
- Persisting irregular bleeding after optimisation or causing symptomatic iron-deficiency.
- LNG-IUD is excellent rescue for Cu-IUD menorrhagia.
5. Counselling & Follow-up Pearls
- Set expectations early – unpredictable bleeding is “normal” in the first months for all progestogen-only methods.
- Amenorrhoea is safe. It does not harm fertility or cause “hormone build-up”.
- Bleeding diary (paper or app) helps reassure patient and guide review.
- Efficacy unaffected by nuisance bleeding provided regimen is followed.
- Review sooner if:
- soaking > 1 pad/hour
- inter-menstrual bleeding after intercourse
- malodorous discharge or pelvic pain
- amenorrhoea > 6 wks on CHC (rule out pregnancy)
- Document advice, plan and review date (usually 3 mths).
6. Key Take-Home Messages
- Mechanism drives bleeding: endometrial atrophy vs hormone withdrawal, not simply “strength” of contraception.
- LNG-IUDs: high local progesterone → thin lining → many users stop bleeding, despite ongoing ovulation.
- Systemic progestogen methods vary—DMPA ultimately gives most amenorrhoea, but POP/implant often cause troublesome spotting early.
- Most irregular bleeding settles by 6 months; manage symptoms while waiting, then investigate if persisting.
- NSAIDs and tranexamic acid are first-line for heavy flow; short progestin or COCP courses for persistent spotting.
- Counselling at initiation is the single strongest predictor of continuation and satisfaction.
START
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┌────────────────────────────────────────────────────────┐
│ 1. Identify contraceptive METHOD & TIME SINCE START │
│ • CHC (pill / ring / patch) │
│ • Progestogen-only pill (traditional / DSG / DRSP) │
│ • Implant ─ Implanon NXT® │
│ • Depot-MPA (DMPA) │
│ • LNG-IUD (Mirena®, Kyleena®) │
│ • Copper IUD │
└────────────────────────────────────────────────────────┘
│
▼
┌────────────────────────────────────────────────────────┐
│ 2. MATCH MECHANISM → EXPECTED BLEEDING PATTERN │
│ ─ CHC → regular withdrawal bleed │
│ ─ LNG-IUD / high-local progestin → light / none │
│ ─ Systemic PO progestin (POP, implant) → spotting │
│ ─ DMPA → early irregular → later amenorrhoea │
│ ─ Copper IUD → heavier, crampy but regular │
└────────────────────────────────────────────────────────┘
│
▼
┌────────────────────────────────────────────────────────┐
│ 3. OBSERVED pattern within FIRST 3–6 MONTHS? │
└────────────────────────────────────────────────────────┘
┌───────────────┴───────────────┐
│ │
▼ ▼
┌────────────────────────────┐ ┌────────────────────────────┐
│ YES – matches expectations │ │ NO (≥6 m OR red-flags) │
│ • Reassure & diary │ └────────────────────────────┘
│ • Explain “random” bleeds │ │
│ (thin / fragile lining) │ ▼
│ • Symptomatic Tx │ ┌────────────────────────────┐
│ – NSAID / tranexamic │ │ 4. FULL ASSESSMENT │
│ – Short MPA / COCP cover │ │ • Compliance / drug int’x │
│ │ │ • Exclude pregnancy, STI │
│ Review at 3 m │ │ • Pelvic USS ± endometrium │
└────────────────────────────┘ │ • Hb / ferritin │
└────────────────────────────┘
│
▼
┌────────────────────────────────┐
│ 5. TREAT ACCORDING TO PATTERN │
│ • Heavy flow → NSAID / TA │
│ • Spotting LARC → 5 d MPA or │
│ 20 d COCP │
│ • DMPA bleed → 10-wk reinject │
│ • CHC BTB → ↑EE / new progestin│
└────────────────────────────────┘
│
▼
┌────────────────────────────────┐
│ 6. REASSESS SATISFACTION │
│ • Acceptable → continue & FU │
│ • Unacceptable / iron-defic. → │
│ switch method (e.g. LNG-IUD) │
└────────────────────────────────┘
│
▼
END