Contraception: Hormonal and Intrauterine Devices

Contraception is the deliberate prevention of pregnancy, and hormonal and intrauterine methods are the most effective reversible options available. Combined hormonal contraceptives (pill, patch, or ring) pair an estrogen with a progestin and work mainly by suppressing ovulation; progestin-only methods (pill, injection, implant, or hormonal intrauterine system) avoid estrogen entirely and are appropriate whenever estrogen is contraindicated, poorly tolerated, or simply not preferred; and the copper intrauterine device is a highly effective, fully non-hormonal option that also works as emergency contraception.^[1] Method choice is a patient-centred decision that weighs effectiveness, individual medical eligibility (chiefly venous thromboembolism and cardiovascular risk with estrogen-containing methods), route and regimen preference, non-contraceptive benefits, and the patient's own plans for future fertility — and pharmacists are frequently the first point of contact for missed-dose questions, drug-interaction concerns, and adverse-effect troubleshooting that ultimately determine whether a method is continued or abandoned.

How this chapter is organized

Unlike most chapters in this reference, there is no disease to recognize here — the clinical task is method selection, initiation, and troubleshooting for a patient who needs pregnancy prevention. Typical encounters include a patient starting contraception for the first time, a patient switching methods because of side effects or a change in medical eligibility (a new migraine with aura, a new VTE, or a desire for pregnancy), a postpartum or postabortion patient, or a patient reporting a missed dose, a suspected drug interaction, or unscheduled bleeding on an existing method.

The following factors change — or eliminate — eligibility for estrogen-containing (combined hormonal) contraception specifically; progestin-only methods and the copper IUD remain appropriate options for almost all of them.^[2]

• Current pregnancy.
• Current or past venous thromboembolism or pulmonary embolism, or a known thrombogenic mutation (factor V Leiden, prothrombin gene mutation) or protein C, protein S, or antithrombin deficiency.
• Migraine with aura, at any age.
• Age over 35 and smoking 15 or more cigarettes per day.
• Uncontrolled hypertension, or a systolic BP ≥160 mmHg or diastolic ≥100 mmHg.
• Diabetes with microvascular complications (nephropathy, retinopathy, neuropathy) or other vascular disease.
• Current or past breast cancer or another hormone-sensitive cancer.
• Complicated valvular heart disease, ischemic heart disease, or history of stroke.
• Severe cirrhosis or an active liver tumour.
• Fewer than 6 weeks postpartum, particularly if breastfeeding.
• Obesity — independently raises VTE risk with estrogen-containing methods, and may reduce transdermal patch efficacy at higher body weight.
• Immobility, recent major surgery, or another transient period of elevated VTE risk.
• Use of an enzyme-inducing medication that can reduce hormonal contraceptive effectiveness.

History

• Full medical, surgical, and gynecologic history, including migraine (and whether it includes aura), VTE/thrombophilia, hypertension, diabetes, liver disease, and any hormone-sensitive cancer.
• Smoking status and, if applicable, cigarettes per day.
• Breastfeeding status and time since delivery.
• All current medications and natural health products, specifically screening for enzyme-inducing agents and GLP-1 receptor agonists.
• Menstrual history, and whether heavy menstrual bleeding, dysmenorrhea, endometriosis, acne, or PMDD symptoms exist that a chosen method might also help manage.
• Prior contraceptive methods tried, reason for discontinuation, and adherence pattern or risk of nonadherence.
• Desire and timeline for future fertility.

Examination and investigations

• Pregnancy test whenever there is any uncertainty about current pregnancy status.
• Weight.
• Blood pressure — required before starting a combined hormonal method.
• Bimanual examination and cervical inspection before IUD insertion.
• STI screening before IUD insertion when risk factors are present; insertion should not otherwise be delayed pending results in a low-risk patient.

When testing is not required

Routine STI screening, Pap testing, or a pelvic examination are not required before starting the pill, patch, ring, implant, or DMPA in a patient without specific risk factors or symptoms — initiation should not be delayed to obtain them.^[4]

• Prevent unintended pregnancy, matched to the patient's own effectiveness expectations and tolerance for a user-dependent method versus a fit-and-forget method.
• Select a method the patient can and will use correctly and consistently — the most effective method on paper provides no benefit if it is discontinued or used incorrectly.
• Avoid estrogen-containing methods in anyone with a contraindication to estrogen.
• Deliver a relevant non-contraceptive benefit — bleeding control, acne, dysmenorrhea, or endometriosis symptom control — when it matters to the patient's other goals.
• Preserve a return to fertility on a timeline that matches the patient's own plans.
• Address STI protection separately, since no hormonal or intrauterine method provides any protection against sexually transmitted infection.

• No hormonal or intrauterine method protects against sexually transmitted infection — counsel correct, consistent external condom use for STI protection regardless of the primary contraceptive method chosen.^[1]
• Correct-use counselling is method-specific: take the pill at the same time daily; apply the patch to dry, intact skin of the buttock, abdomen, upper outer arm, or upper torso and rotate the site each week; insert the ring so it is comfortable (exact position does not affect efficacy) and leave it in place continuously for 3 weeks.
• Offer a quick-start initiation (start today, same visit) rather than asking the patient to wait for their next period or a Sunday, and prescribe up to a year's supply where feasible — both measures reduce gaps in coverage and improve continuation.
• Discuss long-acting reversible contraception (implant, LNG-IUS, copper IUD) proactively with adolescents and any patient at higher risk of inconsistent use — these methods are safe in nulliparous patients of any age and do not require ongoing patient action.
• For patients on long-term DMPA, discuss bone mineralization, particularly if the patient has a low body weight or other osteoporosis risk factors — this is a conversation, not a reason to withhold the method.
• Extended or continuous combined hormonal regimens (no hormone-free interval, or a hormone-free interval no longer than 7 days) reduce total bleeding days and can improve dysmenorrhea, endometriosis-related pain, and cyclical symptoms such as headache and bloating; counsel that unscheduled spotting is the main trade-off, and that continuous use removes the withdrawal bleed that would otherwise signal a missed period.
• Patients with a known Zika virus infection or exposure should use condoms or abstain from vaginal intercourse for 6 months before attempting conception, or for the duration of pregnancy, since Zika can be transmitted through semen.
• Reassure patients that combined hormonal contraceptives do not need a backup method when taking antimicrobials that are not enzyme inducers — this includes penicillins, tetracyclines, macrolides, fluoroquinolones, and imidazole antifungals; the belief that all antibiotics reduce contraceptive efficacy is a persistent myth not supported by current evidence, though vomiting or diarrhea from any illness or antibiotic side effect can itself reduce absorption and does warrant backup precautions.^[3]

Pregnancy

No hormonal or intrauterine contraceptive method is used during an established, desired pregnancy. If pregnancy is confirmed while a method is in place, discontinue combined hormonal methods; for an IUD, assess for ectopic pregnancy and, if the pregnancy is intrauterine and the strings are visible, removal is generally recommended to reduce the risk of miscarriage and infection. Epidemiologic study has not found an increased risk of birth defects with inadvertent early-pregnancy exposure to any of these methods.

Breastfeeding and the postpartum period

Progestin-only methods (pill, DMPA, implant, LNG-IUS) are recommended for postpartum patients regardless of breastfeeding status, given their lower thromboembolism risk in the puerperium and neutral effect on milk supply, and can be started immediately after delivery; the drospirenone-only pill is the one exception, best avoided immediately postpartum until more safety data accumulate. Combined hormonal methods should be avoided for the first 6 weeks postpartum in anyone breastfeeding or with a VTE risk factor, and can generally be started at 3 weeks postpartum in patients who are not breastfeeding.^[3] An IUD may be inserted immediately postpartum (vaginally or at cesarean section) or after a first- or second-trimester abortion, though expulsion and perforation rates are somewhat higher with immediate postpartum insertion than with insertion at the 6-week visit; ensure good fundal placement, which can be technically more difficult in the larger immediate postpartum uterus.^[6]

Adolescents

LARC methods (implant, LNG-IUS, copper IUD) are the preferred first-line option in adolescents at high risk of contraceptive failure from inconsistent use, and are safe in nulliparous adolescents of any age.

Obesity

Combined hormonal methods remain appropriate in most patients with obesity, but obesity is an independent VTE risk factor that should be weighed alongside other risk factors, and the transdermal patch may be less effective at body weight 90 kg or greater — consider an alternative combined method or a LARC option in this situation.

HIV

IUDs do not increase the risk of acquiring HIV compared with no contraceptive method, and DMPA and the LNG-IUS maintain contraceptive efficacy during antiretroviral therapy; some antiretrovirals can interact with combined hormonal pills, so review the regimen before prescribing. Spermicide containing nonoxynol-9 provides no protection against HIV regardless of formulation or dose, and consistent external condom use remains essential for HIV and other STI protection alongside any contraceptive method chosen.

Renal and hepatic impairment

Active liver disease, cholestasis, and liver tumours are contraindications to estrogen-containing methods; progestin-only pills and DMPA are also relatively contraindicated in significant hepatic impairment given hepatic metabolism, while the copper IUD and LNG-IUS are reasonable options since they act locally. The drospirenone-containing progestin-only pill is contraindicated in renal impairment given its antimineralocorticoid activity and hyperkalemia risk.

Mood disorders

Current eligibility criteria do not recommend against hormonal contraceptive use in patients with a history of depression or another mood disorder; monitor for new or worsening depressive symptoms after starting any hormonal method, particularly in adolescents.

• Recheck blood pressure and reassess tolerability within the first few months of starting a combined hormonal method, then at routine intervals thereafter.
• Reassess adherence, side effects, and satisfaction at each visit — the best method is the one the patient will actually continue to use correctly.
• For DMPA, track the reinjection date and reinject no later than 13 weeks after the previous injection; discuss bone health with long-term (multi-year) use.
• For an IUD, teach the patient to check for the strings periodically and to report any change; a routine follow-up visit is reasonable after the first menses or within a few months of insertion to confirm correct placement.
• Reassure patients that unscheduled bleeding and spotting are common in the first 3 to 6 months of any new hormonal method and typically improve with continued use.
• For a new, persistent, or worsening headache, reassess whether it is the self-limiting first-cycle type or a red-flag symptom requiring urgent evaluation.

1. Confirm the method is being used correctly and consistently — timing of the pill, patch/ring change schedule, DMPA reinjection interval, or (for an IUD) that strings are still visualized — before assuming the method itself has failed.
2. Screen for an interacting medication (enzyme inducer, or a GLP-1 agonist during dose escalation) or a recent illness with vomiting/diarrhea that could have reduced absorption.
3. For persistent or new-onset breakthrough bleeding on a combined pill, increase to a formulation with up to 35 mcg ethinyl estradiol or change the progestin type; for bleeding on a continuous regimen, stop active pills for 3 to 4 days, then resume.
4. For persistent LNG-IUS-related spotting beyond the first few months, a short course of NSAIDs or tranexamic acid around the expected bleeding days is a reasonable adjunct, though evidence for either is mixed; rule out malposition or expulsion first if bleeding is new or has changed pattern.
5. For new-onset amenorrhea, rule out pregnancy before reassuring the patient that amenorrhea is an expected and common effect of several methods (LNG-IUS, DMPA, implant, continuous-regimen combined pills, continuous ring use).
6. For persistent or bothersome bleeding after 3 to 6 months despite reassurance and first-line management, or for any adverse effect that is unacceptable to the patient, switch methods rather than continuing to manage around it — discontinuation of an unwanted method is itself a leading cause of unintended pregnancy.
7. For suspected IUD expulsion or malposition (cannot visualize strings, strings feel different, new pain, or bleeding), confirm position with ultrasound before assuming ongoing contraceptive protection.

• Prescribing a combined pill, patch, or ring to a patient with migraine with aura — this is an absolute contraindication because of stroke risk, not a relative caution.
• Telling a patient that any antibiotic requires backup contraception — only rifampin and rifabutin (and the anticonvulsant/antiepileptic enzyme inducers) meaningfully reduce hormonal contraceptive effectiveness; other antimicrobials do not.
• Delaying LARC insertion or hormonal method initiation to obtain a Pap test, pelvic examination, or routine STI screening in a patient without specific risk factors.
• Missing the GLP-1 agonist interaction — tirzepatide can reduce oral contraceptive absorption during dose escalation and needs backup contraception counselling.
• Assuming a single missed combined pill requires backup contraception — it does not; backup is needed only for 2 or more missed pills, or for a norethindrone progestin-only pill taken more than 3 hours late.
• Treating expected, long-term-monitored DMPA-associated bone mineral density change as itself a reason to withhold or stop the method rather than a factor to discuss and monitor.
• Confusing the levonorgestrel-only emergency contraceptive pill (Plan B) with the levonorgestrel intrauterine system (Mirena/Kyleena) — they are entirely different formulations, doses, and use cases.
• Overlooking that a copper IUD is itself a highly effective emergency contraceptive option when inserted within 7 days of unprotected intercourse.
• Failing to offer LARC options to nulliparous or adolescent patients out of an outdated assumption that these methods are unsuitable in that population.

How to use this table: Doses are adult doses for patients of reproductive age; confirm patient-specific eligibility against the medical eligibility criteria above before prescribing. Select any drug name to open its complete Pharmasist Drug Database page.

Combined oral contraceptives — monophasic

All products in this class pair an estrogen with a single, constant progestin dose across the pack. Absolute contraindications common to every product in this class: current or past VTE/PE, known thrombophilia, migraine with aura, age over 35 with heavy smoking, uncontrolled hypertension, current or past breast cancer, complicated valvular or ischemic heart disease, stroke history, severe cirrhosis or liver tumour, and fewer than 6 weeks postpartum. Common class-wide adverse effects: breakthrough bleeding/spotting, nausea, bloating, breast tenderness, headache, and mood change — watch for the ACHES warning signs of a serious vascular event. Common class-wide interactions: enzyme-inducing anticonvulsants, rifampin, rifabutin, and St. John's wort reduce effectiveness; tirzepatide may reduce absorption during dose escalation.

Combined oral contraceptives — extended/continuous cycle

Same estrogen/progestin pairing and contraindications as the equivalent monophasic product, packaged for a longer active-tablet run to reduce the number of withdrawal bleeds per year.

Transdermal patch

Vaginal ring

Progestin-only pills

No estrogen, so the absolute contraindications above (VTE, migraine with aura, smoking-plus-age, uncontrolled hypertension, valvular/ischemic heart disease, severe cirrhosis/liver tumour) largely do not apply; the trade-off is a narrower or more product-specific missed-dose window.

Progestin-only implant

Progestin-only injectable

Intrauterine devices — copper (non-hormonal)

No hormonal contraindications apply since there is no systemic hormone exposure; local contraindications are pregnancy, undiagnosed abnormal vaginal bleeding, current pelvic infection or STI, cervical or endometrial malignancy, copper allergy, and an anatomy that prevents correct placement or retention. No Pharmasist Drug Database monograph exists for these devices — they carry Health Canada device licences rather than a drug product monograph.

Intrauterine devices — hormonal (levonorgestrel intrauterine system)

Local contraindications: pregnancy, current or recurrent pelvic infection, undiagnosed abnormal vaginal bleeding, uterine or cervical malignancy, cervicitis, acute liver disease, and an anatomy that prevents correct placement. This is not the same product as the levonorgestrel emergency contraceptive pill (Plan B) — do not confuse the two. No Pharmasist Drug Database monograph specific to the intrauterine formulation exists, so these rows are not linked.