14. Hormonal Contraception

What is hormone-based contraceptives?

• A variety of hormonal contraceptive methods are available

• Although highly effective at preventing pregnancy, hormonal methods do not offer protection against STIs

What is Progestogen?

Umbrella term

• Progesterone – natural hormone

• Progestogen/Progestin – can also include synthetic versions

What are intrauterine devices?

• IUD: Device inserted inside the uterus; T-shaped, fans out in uterus.

• Types: Progestogen (hormonal) IUD.

• Mechanism:

  • Delivers steady daily hormone.

  • HPG axis adjusts → silences natural hormonal fluctuations.

  • Eliminates natural cycle peaks and dips; body senses constant hormone levels.

What are progestogen IUDs?

Levonorgestrel IUD - common progestin in IUDs

• Releases progestin regularly, providing steady hormone level

Mechanism/Onset of Action

• Foreign body at uterus prevents fertilization, impairs sperm transport

• Slow release of levonorgestrel causes thickening of cervical mucus, antiproliferative effect on endometrium and suppression of ovulation

Therapeutic Regimen

• Inserted by a trained clinician and replacement depends on product expiry (3 vs. 5 years)

How do 28-day combined hormonal contraceptive tablets work and why is there a 7-day hormone-free period?

• Structure: 28-day pack → 21 days of hormone + 7 days no hormone.

• Mechanism:

  • 21 days: Steady hormonal support → suppresses natural cycle fluctuations.

  • Prevents thickening of endometrium → lighter periods.

• 7 days hormone-free:

  • Causes light withdrawal bleeding (“period”).

  • Originally included for user comfort/normalcy based on clinical trial feedback.

• Clinical impact: Heavy periods are reduced because endometrial lining doesn’t thicken much.

What are estrogen and progestogen combinations?

Combined Oral Contraceptives (COCs) a.k.a. “The Pill”

• Contain varying amounts of estrogen & progestogens

• Different options available

• Mechanisms of Action

  • Primarily inhibits ovulation

  • Thickens cervical mucus

  • Interfere with fertilization by altering tubal motility of ovum

  • Inflammation and atrophy of the endometrial lining

What is monophasic, biphasic, and triphasic?

• Monophasic: Fixed Dose. Same estrogen/progestogen dose for 21 days

• Biphasic: Usually estrogen stays constant, progestogen increases halfway

• Triphasic: Estorgen and/or progestogen levels change each week

• Purpose of variations: Tailored for individual tolerance; can reduce side effects like headaches, bloating, mood changes, tiredness.

• Special considerations:

  • People with family history of blood clots, stroke, or cardiovascular disease may use progestin-only pills to avoid estrogen-related risks.

What do POPs (Progestin-only pills) do?

• POPs thicken cervical mucus, making it difficult for sperm to swim into the uterus or to enter the fallopian tube

• POPs alter the normal cyclical changes in the uterine lining and may result in unscheduled or breakthrough bleeding (disrupting uterine lining → prevents implantation)

• Some may inhibit ovulation – although not consistently

What are hormones and non-oral routes?

• Depo-Provera

  • Slow-release progestogen, administered by injection and lasts 3 months (sits in the muscle and is slowly released)

• Transdermal patches

  • Contain an estrogen and progestogen, with replacement every week

• Vaginal rings

  • Release a combination of an estrogen and a progestogen and remain in place for three weeks

• Implantable rods

  • Release progestogen and are extremely reliable, replaced every three years

What is Depo-Provera?

• Injectable progestogen

What is Depot Medoxyprogesterone Acetate (DMPA)?

Commonly known as Depo-Provera

• Can be considered if estrogen is contraindicated/poorly tolerated (ex: symptoms/clinical history of cardiovascular disease or blood clots)

• Mechanism/Onset of Action

  • Suppresses ovulation

  • Absorbed slowly from injection site

• Therapeutic Regimen: Injected intramuscularly every 3 months

What is the Ortho Evra Patch?

• Replace every week

• Contain varying amounts of ethinyl estradiol and norelgestromin (synthetic progestogen)

• Mechanisms of Action

  • Primarily inhibits ovulation

  • Thickens cervical mucus

  • Interfere with fertilization by altering tubal motility of ovum

  • Inflammation and atrophy of the endometrial lining

What is the NuvaRing?

• 21 days inside with a 7-day free break

• Contain varying amounts of ethinyl estradiol and etonogesteral (synthetic progestin)

• Mechanisms of Action

  • Primarily inhibits ovulation

  • Thickens cervical mucus

  • Interfere with fertilization by altering tubal motility of ovum

  • Inflammation and atrophy of the endometrial lining

What is Implanon and how does it work?

• Implanon: Subdermal rod containing synthetic progestin (lab-made progesterone).

• Mechanism: Placed just under the skin → slowly releases hormone over time.

• Purpose: Provides steady hormonal contraception; choice can be adjusted based on individual tolerance or side effects.

How does the Behavioural (fertility awareness) Method of contraception work, and what are its limitations?

• Method: Track menstrual cycle (usually ~28 days) → avoid sex during possible ovulation window (~day 8–16).

• Considerations: Sperm can survive several days; ovulation timing varies, especially with irregular cycles.

• Limitations: Unreliable alone; best used in combination with hormonal contraceptives.

What is emergency hormonal contraception?

• Progestogen-Only (Levonorgestrel) or “Plan B”

• Ulipristal acetate (UPA)

What is Progestogen-Only (Levonorgestrel) or “Plan B”?

• Mechanism of Action

  • Inhibits ovulation, thickening of cervical mucus, interference with implantation. No effect on existing pregnancy.

  • Most effective within 72 hours of unprotected intercourse or suspected contraceptive failure (the earlier the better). May be effective up to 5 days.

• Therapeutic Regimen: 1 complete dose to be taken as soon as possible after unprotected intercourse or suspected contraceptive failure (ideally within 72 hours).

What is Ulipristal acetate (UPA) - Ella One?

• Mechanism of Action

  • Prevents progesterone from occupying its receptor by competitive inhibition

  • Inhibits/delays ovulation by preventing LH peak and postponing follicular rupture

  • Most effective within 120 hours of unprotected intercourse or suspected contraceptive failure (the earlier the better)

• Therapeutic Regimen: 1 complete dose to be taken within 120 hours of unprotected intercourse or suspected contraceptive failure

• Drug Interactions: Consider avoiding use with CYP 3A4 P450 inducers and other hormonal contraceptives (anti-seizure, HIV treatment/antiretroviral drugs, narcolepsy medication)