Contraceptive Methods, Bleeding Patterns

Core principle

Contraception-related bleeding is usually due to endometrial effects rather than a “true period”. Bleeding changes are common with hormonal contraception, especially in the first 3–6 months, but pregnancy, infection, cervical pathology and uterine pathology must be considered when bleeding is persistent, new after stability, heavy, postcoital, painful or clinically concerning.

1. Normal menstrual physiology — benchmark

Phase	Dominant hormone	Endometrial effect	Bleeding mechanism
Follicular phase	Rising oestrogen	Proliferation of functional endometrium	No bleeding unless endometrium unstable
Luteal phase	Progesterone after ovulation	Secretory transformation and stabilisation	Progesterone maintains lining
Menses	Fall in oestrogen and progesterone	Spiral arteriole constriction, ischaemia and shedding	Abrupt hormone withdrawal triggers bleeding

Key concept: contraceptives alter bleeding by suppressing ovulation, changing hormone withdrawal, or causing endometrial atrophy/instability.

2. Bleeding patterns by contraceptive method

Method	Main mechanism	Expected bleeding pattern	Clinical explanation
Combined hormonal contraception: COCP, vaginal ring, patch	Suppresses ovulation; provides oestrogen + progestogen; hormone-free interval produces withdrawal bleed	Usually predictable withdrawal bleeding; breakthrough bleeding common early or with missed pills	Missed pills or low hormone exposure can cause unscheduled withdrawal bleeding. Persistent bleeding after initial months needs assessment.
Traditional progestogen-only pill	Thickens cervical mucus; variable ovulation suppression	Irregular bleeding, spotting or prolonged light bleeding	Low-dose progestogen causes a thin but relatively unstable endometrium.
Desogestrel / drospirenone POP	More consistent ovulation suppression than traditional POP	Irregular bleeding is still common; amenorrhoea may occur	Bleeding does not imply reduced contraceptive efficacy if taken correctly.
Etonogestrel implant — Implanon NXT®	Continuous systemic progestogen with ovulation suppression and endometrial effects	About : 1/5 amenorrhoea, 3/5 infrequent or irregular bleeding, 1/5 frequent or prolonged bleeding	Pattern is unpredictable; nuisance bleeding is common but not harmful after other causes are excluded.
DMPA injection	Strong/near-complete ovulation suppression, progressive endometrial atrophy, and relative hypo-oestrogenism	Irregular, frequent or prolonged bleeding is common initially; amenorrhoea becomes increasingly common with continued use	Family Planning Alliance Australia guidance: ~1/2 amenorrhoea, ~1/6 infrequent irregular bleeding, ~1/3 frequent/prolonged bleeding; amenorrhoea increases over time.
LNG-IUD — Mirena®, Kyleena®	High local levonorgestrel effect on endometrium; ovulation often continues	Frequent spotting/irregular bleeding in first 3–6 months, then lighter bleeding or amenorrhoea	Local endometrial suppression causes glandular atrophy/decidualisation; reduced bleeding over time is expected.
Copper IUD	Non-hormonal; local inflammatory contraceptive effect	Regular cycles but may be heavier, longer or more painful	Ovarian cycle continues; copper IUD can increase menstrual blood loss and dysmenorrhoea.
Barrier methods / sterilisation	No endocrine effect	Native menstrual pattern should continue	New abnormal bleeding should be investigated as abnormal uterine bleeding, not attributed to the method.

3. Why LNG-IUDs often reduce or abolish bleeding

LNG-IUDs deliver levonorgestrel mainly to the endometrium.

This causes endometrial glandular atrophy and stromal decidualisation, so even if ovulation continues, there is little functional endometrium to shed.

Therefore, spotting is common early, but bleeding usually becomes lighter with time and amenorrhoea is common.

4. Mechanistic comparison of progestogen-only methods

Factor	LNG-IUD	Implant	POP	DMPA
Delivery	Local intrauterine	Systemic subdermal	Systemic oral	Systemic IM/SC
Endometrial effect	Marked local atrophy	Thin, unstable endometrium	Thin/unstable endometrium	Progressive endometrial atrophy
Ovarian effect	Ovulation often continues	Ovulation usually suppressed	Variable depending on POP type	Ovulation strongly suppressed
Typical bleeding	Spotting early → light/amenorrhoea	Unpredictable	Unpredictable	Irregular early → amenorrhoea over time

5. GP assessment of bleeding on contraception

Initial checklist

Assess:

Method used, start date, expiry date and recent changes.
Bleeding pattern: timing, duration, volume, clots, flooding, postcoital bleeding, intermenstrual bleeding.
Pregnancy risk: missed pills, delayed injection, late ring/patch change, vomiting/diarrhoea, interacting medicines.
STI risk: new partner, multiple partners, pelvic pain, discharge.
Cervical screening history.
Symptoms of anaemia.
Pelvic pain, dyspareunia, fever or malodorous discharge.
Risk factors for endometrial pathology: age ≥45 years, obesity, PCOS/chronic anovulation, tamoxifen use, Lynch syndrome, diabetes, nulliparity, persistent abnormal bleeding.

Pregnancy should be excluded in any patient with abnormal bleeding on contraception where clinically relevant.

6. Investigation approach

Situation	Suggested assessment
Expected bleeding pattern within first 3–6 months and no red flags	Reassure document, bleeding diary review
Persistent bleeding beyond 3–6 months	Pregnancy test STI testing if risk cervical screening status consider speculum examination FBC/ferritin, pelvic ultrasound
Sudden change after previously stable pattern	Exclude pregnancy infection IUD malposition/expulsion cervical pathology and uterine pathology
Heavy bleeding	FBC/ferritin pregnancy test consider pelvic ultrasound treat iron deficiency
Postcoital bleeding	Speculum examination STI testing cervical co-test where indicated persistent/recurrent PCB requires gynaecology/colposcopy pathway according to cervical screening guidance.
Persistent intermenstrual bleeding	Cervical co-test STI testing if risk pelvic ultrasound and consider gynaecology referral.
Age ≥45 years or endometrial cancer risk factors	Consider endometrial assessment including ultrasound and/or endometrial biopsy depending on clinical scenario.

7. Red flags — do not simply reassure

Investigate or refer if:

Positive pregnancy test or pregnancy symptoms.
Postcoital bleeding.
Persistent unexplained intermenstrual bleeding.
New bleeding after a stable pattern or after amenorrhoea.
Persistent bleeding beyond 6 months.
Heavy bleeding causing symptoms or iron deficiency.
Pelvic pain, dyspareunia, fever or offensive discharge.
Abnormal cervix on examination.
Age ≥45 years with abnormal bleeding.
Risk factors for endometrial cancer.
Suspected PID or STI.

Postcoital bleeding and persistent unexplained intermenstrual bleeding have specific cervical screening and referral pathways in Australia.

8. Symptomatic management after excluding important pathology

General counselling

Irregular bleeding is common in the first months of progestogen-only contraception and may settle without treatment.
Amenorrhoea on hormonal contraception is generally safe and does not indicate retained blood or infertility.
Bleeding does not reduce contraceptive efficacy if the method is used correctly.

Medication options

Scenario	Option	Notes
Heavy/prolonged bleeding with progestogen LARC	NSAID for 5 days, e.g. mefenamic acid if suitable	Avoid/consider risk in renal disease, peptic ulcer disease, anticoagulation, NSAID allergy. Family Planning guidance supports NSAID use for short-term bleeding control.
Heavy bleeding	Tranexamic acid for up to 5 days if no contraindication	Avoid in active/history high-risk thrombosis situations; use caution with VTE risk.
Troublesome bleeding with implant, DMPA or LNG-IUD	Combined hormonal contraception for 3 months, cyclic or continuous, if medically eligible	Check contraindications: COCP: migraine with aura, VTE risk, smoking age >35, uncontrolled hypertension, breast cancer history.
Implant-related persistent bleeding	Short course NSAID tranexamic acid if heavy, or CHC if eligible	Explain bleeding often recurs after treatment stops.
DMPA bleeding	Consider bringing next injection forward to 10 weeks	Used when troublesome bleeding persists and patient wants to continue DMPA.
Copper IUD heavy bleeding	NSAID and/or tranexamic acid; consider switch to LNG-IUD if unacceptable	LNG-IUD is a good option when contraception and heavy menstrual bleeding management are both desired.
CHC breakthrough bleeding after first 3 cycles	Check adherence first; consider higher EE dose, different progestogen, or different CHC formulation	Exclude pregnancy/STI/pathology if persistent or concerning.

9. When to switch contraception

Consider switching if:

Bleeding remains unacceptable despite counselling and short-course treatment.
Iron deficiency or anaemia develops.
Patient preference changes.
Contraindications develop.
Copper IUD causes unacceptable menorrhagia/dysmenorrhoea.
Patient wants a method more likely to reduce bleeding, e.g. LNG-IUD.

10. Patient explanation

“This bleeding is a common side effect of many contraceptives, especially in the first few months. It usually happens because the lining of the uterus becomes thin and fragile, not because the contraception is unsafe or ineffective. We still need to rule out pregnancy, infection and cervical or uterine problems if the bleeding is persistent, heavy, painful, happens after sex, or changes suddenly.”

Key take-home points

CHC usually gives predictable withdrawal bleeding; missed pills commonly cause breakthrough bleeding.
Progestogen-only methods commonly cause irregular bleeding, especially early.
Implanon NXT® bleeding is unpredictable: roughly 1/5 amenorrhoea, 1/5 frequent/prolonged bleeding, and the rest infrequent/irregular bleeding.
DMPA commonly causes irregular bleeding initially, then increasing amenorrhoea over time.
LNG-IUD commonly causes spotting for 3–6 months, then lighter bleeding or amenorrhoea.
Copper IUD can make periods heavier, longer and more painful.
Always exclude pregnancy, STI/cervicitis, cervical pathology, IUD malposition/expulsion and uterine pathology when bleeding is persistent, new, postcoital, heavy, painful or otherwise concerning.

Duration / replacement Age to stop or review / Return to fertility

Method	Expected bleeding pattern	Duration / replacement	Age to stop or review	Return to fertility
Combined hormonal contraception: COCP, vaginal ring, patch	Usually predictable withdrawal bleeding; breakthrough bleeding common early or with missed pills	Ongoing use while medically eligible; review at least annually and with new risk factors	Generally stop/switch around age 50 because vascular risk rises; use safer alternative such as POP, implant, IUD or barrier method if contraception still required.	Fertility usually returns quickly after stopping; no long-term delay expected.
Traditional progestogen-only pill	Irregular bleeding, spotting or prolonged light bleeding	Daily continuous pill; ongoing use while medically eligible	Can generally be continued until age 55 if medically eligible. RANZCOG notes POP can be used until age 55.	No delay in return to fertility after stopping POP use.
Desogestrel / drospirenone POP	Irregular bleeding is still common; amenorrhoea may occur	Daily continuous pill; ongoing use while medically eligible	Can generally be continued until age 55 if medically eligible.	No delay in return to fertility after stopping POP use.
Etonogestrel implant — Implanon NXT®	About 1/5 amenorrhoea, 3/5 infrequent or irregular bleeding, 1/5 frequent or prolonged bleeding	Effective for 3 years; replace every 3 years or remove earlier if desired.	Can be used through reproductive years; in perimenopause can generally continue until menopause/age 55 if medically eligible, but replace if expired.	Fertility returns quickly after removal; periods usually return to normal within about 1 month.
DMPA injection	Irregular bleeding early; amenorrhoea becomes more common over time. 1/2 amenorrhoea 1/6 infrequent irregular bleeding 1/3 frequent /prolonged bleeding.	Injection every 12 weeks; troublesome bleeding may improve by shortening interval to 10 weeks.	Review risks regularly; Queensland guidance notes DMPA is not first-line in adolescents or perimenopausal women because of bone mineral density concerns, and women continuing DMPA should have benefits/risks reviewed every 2 years. Around age 50, generally switch to another method.	Return to fertility may be delayed. Australian Prescriber advises counselling that fertility may take up to 12 months to return; older Family Planning material notes delay can be up to 18 months, but no long-term reduction in fertility.
LNG-IUD — Mirena® 52 mg, Kyleena® 19.5 mg	Frequent spotting/irregular bleeding in first 3–6 months, then lighter bleeding or amenorrhoea	Mirena®: contraception for 8 years in Australia; HMB indication remains 5 years unless clinically appropriate to continue. Kyleena®: 5 years; extended use beyond 5 years not recommended.	Any 52 mg LNG-IUD inserted at age ≥45 years can be used for contraception until age 55; if used as endometrial protection for menopausal hormone therapy, replace every 5 years.	Fertility returns after removal; no long-term delay expected.
Copper IUD	Regular cycles but may be heavier, longer or more painful	Usually 5–10 years, depending on device type. Family Planning efficacy card lists copper IUDs as lasting 5–10 years.	Copper IUD with copper surface area ≥300 mm² inserted at age ≥40 years can be used until menopause; remove 1 year after final menstrual period if ≥50, or 2 years after final menstrual period if <50.	Fertility returns after removal; no long-term delay expected.
Barrier methods	Native menstrual pattern should continue	Used per episode of intercourse; no replacement schedule except product expiry or device-specific care	Can be used until contraception no longer required; non-hormonal methods can usually be stopped after 12 months amenorrhoea if ≥50, or 24 months if <50.	Immediate return to baseline fertility when not used.
Sterilisation	Native menstrual pattern should continue unless other hormonal method stopped	Intended permanent method	No routine “stop age”; remains permanent. Counselling should emphasise permanence and regret risk.	Usually intended irreversible; pregnancy after reversal/IVF depends on individual factors and procedure type.