Contraception - Quick Reference Notes

Introduction to contraception

  • Definition: methods to prevent pregnancy by interfering with ovulation, fertilization, and implantation.
  • Importance: enables family planning, reduces unintended pregnancies, improves reproductive health. Worldwide rapid population growth is a concern; faster growth in developing countries (~96\%) highlights need for effective contraception. Contraception ≠ fertility control; related but not identical concepts.

Key features of a good contraceptive method

  • Efficacy
  • Safety
  • Reversibility
  • Ease of use
  • Manageable or minimal side effects
  • Effectiveness in STI prevention
  • Accessibility and cost
  • Minimal interference with daily life
  • Non-contraceptive benefits
  • Cultural/personal acceptance
  • Compatibility with other medications

Effectiveness and use

  • Effectiveness depends on: method efficacy, user compliance, and continuation.
  • Methods requiring no ongoing user compliance after insertion have similar perfect-use and typical-use failure rates.
  • Discontinuation is lower for methods that do not require removal by a provider; common reasons include perceived risks and side effects.

Medical eligibility for contraception (MEC)

  • Most users are young and healthy and can safely use most methods.
  • WHO MEC criteria classify conditions into four categories (1–4):
    • Category 1: no restriction for use
    • Category 2: advantages outweigh risks
    • Category 3: risks generally outweigh advantages
    • Category 4: unacceptable health risk; use generally not recommended
  • UK MEC example: categories assigned per condition (1–4) guiding method choice.

Failure rates (12 months)

  • Typical-use vs perfect-use differences exist for many methods; some insertable methods have near-equal rates for both.
  • Examples (illustrative, from the table):
    • Implants (Implanon): ~0.01\% per 100 woman-years (both perfect and typical use)
    • LNG-IUS: ~0.1\% per 100 woman-years
    • Copper IUD (Cu-T 380A): ~0.6\%--0.8\%
    • Progestin-only pills (POP): higher typical-use failure than CHCs
    • Combined oral contraceptives (COCs): typical-use higher than perfect-use; common figures around the low single digits to ~1-2\% depending on regimen and adherence
    • Male condom: typical-use ~15\%; perfect-use ~2\%
    • Withdrawal: ~27\% typical; ~4\% perfect (greatly variable by user)
    • No method: ~85\% per 100 WY
    • Natural methods (calendar, temperature, mucus): ~20-30\% typical; ~3-4\% perfect
  • Note: overall, highly effective methods are implants, LNG-IUS, copper IUD, and sterilization; barriers and natural methods vary more with adherence.

Types of contraception

A. Hormonal methods

  • Combined hormonal contraceptives (CHCs): estrogen + progestin
  • Progestin-only contraceptives (POPs): progestin alone
  • Methods include:
    • Pills (COCs)
    • Patches
    • Vaginal rings
    • Progestin-only pills
    • Injectables
    • Subdermal implants
    • LNG-IUS (hormone-releasing IUD)
    • Emergency contraception (hormonal regimens)

A1. Combined hormonal contraceptives (CHCs)

  • Mechanism of action: inhibit ovulation by suppressing GnRH → FSH/LH; estrogens stabilize the endometrium; progestins thicken cervical mucus and make endometrium unreceptive
  • Regimens: typically 21 days on, 7 days off (21/7); some regimens use 24/4 to improve efficacy with very low doses
  • UK MEC category 4 conditions (examples): breastfeeding <6 weeks postpartum; certain cardiovascular risks; current VTE; migraine with aura; significant liver disease; etc.
  • Advantages: reliable contraception, coitus-independent, rapid return of fertility after discontinuation; plus non-contraceptive benefits (see below)
  • Non-contraceptive benefits: increased bone density, reduced menstrual blood loss, decreased risk of ectopic pregnancy, improved dysmenorrhea, fewer premenstrual symptoms; cancer risk reductions (endometrial/ovarian, colorectal)
  • Side effects (minor): mood changes, headaches, nausea, breast tenderness, breakthrough bleeding, weight changes, chloasma/acne; fluid retention
  • Major risks (serious but uncommon): venous thromboembolism (VTE), arterial disease, cholestasis, gallstones, possible cancer risk changes, liver adenoma; most side effects reverse after stopping (3–6 months for some)
  • Types/examples: pills, patches, vaginal rings
A1a. Pills (combined oral contraceptives, COCs)
  • Composition: estrogen ~20-50\mu g; progestin generations (1st–4th; newer include anti-androgenic options)
  • Regimens: monophasic (same dose each day) or phasic (varying doses)
  • Administration: most regimens 21 days on, 7 days off; quick-start or Sunday-start options; if starting mid-cycle, additional contraception for a period may be advised
  • Missed pills management (brief): if 1 pill missed (≤24 h), take immediately; if 2+ pills missed, take two pills daily for two days and use backup contraception for 7 days
  • Drug interactions: antibiotics and enzyme-inducing drugs can reduce efficacy; use backup contraception when indicated
  • Common brands in examples: Microgynon, Yasmin, Marvelon (composition examples provided in table)
A1b. Patch
  • Weekly application for 3 weeks, then 1 patch-free week
  • Delivers estrogen + progestin systemically; similar contraindications to CHCs
A1c. Vaginal ring
  • Flexible polymer ring releasing ethinyl estradiol + etonogestrel; inserted within 5 days of menses; left in place for 3 weeks, then 1 week off

A2. Progesterone-only contraceptives (POPs)

  • Rationale: avoid estrogen-related side effects; safe in lactation; good for some contraindications to CHCs
  • Methods: progestogen-only pill (mini-pill), injectables (Depot-Provera), subdermal implant (etonogestrel), LNG-IUS
  • Mechanism: primarily cervial mucus thickening and endometrial atrophy; some regimens suppress ovulation (e.g., certain higher-dose progestins)
  • Return to fertility: generally immediate after stopping POPs; injectables may cause a delay (months)
  • Advantages: safe in breastfeeding, few contraindications; highly effective when used correctly
  • Disadvantages: irregular or unpredictable uterine bleeding; ectopic pregnancy risk slightly increased with POPs; acne, breast tenderness, mood changes
  • POP specifics: must take at the same time daily; missing by a few hours reduces effectiveness; high importance of adherence, especially in lactation
  • Injectables: DMPA (Depo-Provera) 150 mg IM every 90 days; may reduce menstrual bleeding; long-term use can affect bone density; not for use in pregnancy or liver disease; return to fertility may be delayed
  • Implant: etonogestrel 75 mg released over years; inserted subdermally in upper arm; highly long-acting and reversible
  • LNG-IUS: levonorgestrel intrauterine system, 5-year efficacy; reduces menstrual bleeding substantially; endometrial changes prevent implantation; possible irregular bleeding initially

A3. Emergency contraception (EC)

  • Indication: post-coital contraception after unprotected intercourse or sexual assault
  • Hormone-based methods:
    • Estrogen–progestin regimens (Yuzpe method): multiple pills within 72 hours; effectiveness higher the sooner given; may cause nausea; vomiting requires a replacement dose
    • Progestin-only regimens (levonorgestrel): Plan B (0.75 mg x 2, 12 hours apart) or Plan B One-Step (1.5 mg single dose); effective up to 72–120 hours
    • Uliprastal acetate (EllaOne): single 30 mg dose up to 120 hours; delays ovulation; more effective than LNG in trials
  • Copper IUD: inserted up to 5 days after intercourse; most effective EC; also provides ongoing contraception for up to 10 years
  • Important notes: EC is not abortion; should not be relied upon as regular birth control; if menses delayed, pregnancy testing advised

B. Non-hormonal contraception

  • Barrier methods: condoms (male and female), spermicides, diaphragm, cervical cup
  • Spermicides: forms include gel, cream, foam; usually used with barrier methods; not reliable as sole method
  • Natural methods (fertility awareness): abstinence during fertile window; basal body temperature, cervical mucus, rhythm/calendar methods; often less reliable without training
  • Lactational amenorrhea (LAM): fully breastfeeding women in first 6 months post-partum can have >98\% protection when exclusive breastfeeding
  • Sterilization: permanent methods via tubal ligation (female) or vasectomy (male)
  • IUDs (intrauterine devices): copper IUDs and LNG-IUS; long-acting, reversible; highly effective; non-daily

C. Intrauterine devices (IUDs)

  • Copper IUD (Cu-T 380A, Multiload 375): non-hormonal; copper acts as sperm toxic/to impair fertilization; inflammatory endometrium prevents implantation; heavier/more painful menses commonly occur; immediate return to fertility after removal
  • LNG-IUS (Mirena): hormonal IUD releasing levonorgestrel (~20\mu g/day); 5-year efficacy; endometrium thinning and cervical mucus thickening; bleeding patterns shift toward lighter, irregular bleeding then oligomenorrhea or amenorrhea
  • Insertion: requires evaluation, aseptic technique, cervical care, uterine sounding, and proper sizing; trained clinician needed; may involve NSAIDs and local anesthetic for pain control
  • Indications/contraindications: similar to other hormonal methods; copper vs LNG-IUS have specific contraindications (e.g., pregnancy, certain uterine or cervical pathologies, active infections)
  • Removal/complications: expulsion, perforation, infection risk; timely removal if adverse effects or desire for fertility; missed threads require imaging/localization procedures (see Missed loop section)
  • Pregnancy with IUD: remove if intrauterine; removal timing depends on gestational age and thread visibility; risk of miscarriage, infection, or preterm birth considered

D. Sterilization

  • Female sterilization: tubal ligation or occlusion; permanent, effective; requires surgical/office procedure (laparoscopy, laparotomy, hysteroscopy)
  • Male sterilization (vasectomy): division of vas deferens; simple, inexpensive; fertility returns after clearance of sperm in semen samples (usually after two consecutive samples at 12 and 16 weeks)

E. Missed threads and pregnancy with IUDs

  • Missed loop workup: pregnancy test first; locate threads with endocervical brush; if not found, uterine cavity probing or hysteroscopy; imaging (ultrasound, X-ray) to localize; if expelled, continue reliable contraception
  • If IUCD is in situ during pregnancy: removal considered if benefits outweigh risks; if displaced high in the uterus, decision individualized; increased risks of miscarriage, infection, prematurity

Practical notes for clinical use

  • Initiation options for CHCs: quick-start (start any day; may require backup contraception for 7 days) or traditional (start with menses or a sunday-start)
  • Regimens: CHCs typically 21 days on, 7 days off; some regimens use 24/4 to optimize low-dose pills
  • Regular follow-up and counseling: discuss side effects, warning signs (VTE symptoms, severe headache with focal neuro symptoms, chest pain), drug interactions, and STI prevention
  • Counseling on method selection should consider age, fertility goals, medical history, breastfeeding status, risk factors, adherence possibility, and patient preferences

Quick reference: method categories and typical characteristics

  • Most effective/long-acting reversible contraception (LARC): Implants, LNG-IUS, copper IUD, sterilization
  • Very effective (low failure with typical use): Injectables, COCs, POPs, patches, vaginal rings
  • Effective but user-dependent: Male/female condoms, diaphragm, cervical cup, fertility awareness methods
  • Least effective without adherence: Spermicides used alone, Withdrawal, rhythm methods without training
  • Emergency contraception: LNG-EC, Yuzpe, ulipristal, Plan B, Copper IUD (within appropriate windows)

Quick examples (numerical quick-look)

  • Male condom: typical-use pregnancies per 100 WY ≈ 15; perfect-use ≈ 2
  • Copper IUD: typical ≈ 0.6-0.8\%; perfect ≈ 0.6-0.8\%
  • LNG-IUS: ≈ 0.1\% (both typical and perfect)
  • Implants: ≈ 0.01\% (very high effectiveness)
  • POPs: higher typical-use failure than CHCs; irregular bleed common
  • Withdrawal: ≈ 20-30\% typical

References to key figures from the material (for quick recall)

  • WHO/UK MEC framework for eligibility and safety
  • UK MEC category examples (categories 1–4 for various conditions)
  • WHO/FRM/FPP MEC guidelines for CHCs indications and contraindications