Comprehensive Guide to Hormonal Contraception and Induced Abortion

Combined Hormonal Contraceptives (CHCs)

• Definition and Composition:
  • Combined hormonal contraceptives contain both an estrogen component and a progestin component.
  • Estrogen Component:
    • Ethinyl Estradiol ($EE$) is the standard synthetic estrogen used in most combined preparations.
    • Natural $17\beta\text{-estradiol}$ produced by the ovaries undergoes rapid first-pass hepatic inactivation when ingested orally.
    • Addition of an ethynyl group at the $C17$ position yields ethinyl estradiol, which resists gastrointestinal and hepatic degradation, enabling oral bioavailability and significantly increasing potency.
    • Standard daily doses of ethinyl estradiol in modern oral contraceptive pills are 20\text{ }\null\mu g, 30\text{ }\null\mu g, and 35\text{ }\null\mu g. Doses of 50\text{ }\null\mu g are considered excessively high for routine contraceptive use and are obsolete.
    • Estetrol ($E4$) is a newer fetal estrogen used in novel oral formulations, demonstrating potentially lower risks of venous thromboembolism and fewer side effects.
  • Progestin Component:
    • Progestins are synthetic compounds derived primarily from testosterone, modified via removal or alteration of the carbon at the $C19$ position to shift activity from androgenic to progestational.
• Epidemiology and Failure Rates:
  • Combined oral contraceptives ($COCs$) remain the most popular reversible contraceptive method in the United States.
  • Typical use failure rate across combined methods (pills, patch, ring) is approximately $9\%$ per year.
• Mechanism of Action:
  • Combined hormonal contraceptives act via negative feedback suppression on the hypothalamic-pituitary-ovarian ($HPO$) axis.
  • Progestin Action: Suppresses the release of Luteinizing Hormone ($LH$) from the anterior pituitary, thereby preventing the pre-ovulatory $LH$ surge and blocking ovulation. Progestin also induces atrophy of the endometrial lining (rendering it unreceptive to implantation) and thickens cervical mucus (creating a barrier to sperm penetration).
  • Estrogen Action: Suppresses Follicle-Stimulating Hormone ($FSH$) release, preventing the selection and maturation of a dominant ovarian follicle. Estrogen also provides stability to the endometrium to minimize breakthrough bleeding.
• Administration Regimens for Oral Contraceptive Pills:
  • $21/7$ Regimen: Consists of $21$ consecutive days of active estrogen/progestin pills followed by a $7\text{-day}$ hormone-free (placebo) interval during which withdrawal bleeding (menses) occurs.
  • $24/3$ Regimen: Consists of $24$ consecutive days of active pills and a $3\text{-day}$ hormone-free interval, producing a shorter monthly withdrawal bleed.
  • Extended/Continuous Regimens: Active hormone pills are taken continuously for $84$ days followed by a $7\text{-day}$ hormone-free interval (resulting in quarterly menses), or taken continuously for $365$ days without placebo intervals to completely suppress menses.
• Pros and Clinical Benefits:
  • High efficacy when taken consistently.
  • Reduces dysmenorrhea, menorrhagia, and pelvic pain.
  • Provides predictable, lighter, and shorter menses.
  • Allows intentional manipulation or suppression of menses for lifestyle or therapeutic reasons.
  • Safe for healthy, non-smoking individuals up to the onset of menopause.
• Cons, Adverse Effects, and Discontinuation:
  • Requires strict daily compliance; missed pills increase the risk of escape ovulation and pregnancy, especially if missed adjacent to the placebo week.
  • Initial Side Effects: Nausea, breast tenderness, bloating, unscheduled breakthrough bleeding or spotting, and headaches. These symptoms typically self-resolve within the first $3$ months of use.
  • Pill-Induced Amenorrhea: Some users do not experience withdrawal bleeding during the placebo week; increasing the estrogen dose slightly can restore withdrawal bleeding if desired for pregnancy reassurance.
  • High rates of premature discontinuation, particularly among adolescent users, often triggered by unscheduled bleeding or fear of side effects.
  • Debunked Adverse Associations: Clinical studies show that combined hormonal contraceptives do not cause significant weight gain or clinical depression compared to non-users; both users and non-users show similar baseline weight trajectories over time.

Transdermal and Vaginal Combined Delivery Systems

• Vaginal Contraceptive Ring (Ethinyl Estradiol / Etonogestrel):
  • Mechanism & Pharmacokinetics: A flexible ring inserted into the upper vagina that continuously releases ethinyl estradiol and etonogestrel. Hormones are absorbed directly across the vaginal epithelium into the systemic circulation, avoiding gastrointestinal degradation and first-pass hepatic metabolism.
  • Produces highly stable, steady-state serum hormone concentrations without the daily peak-and-trough fluctuation seen with oral pills.
  • Standard Regimen: The ring remains in the vagina for $3$ consecutive weeks, followed by $1$ ring-free week to allow withdrawal bleeding. The ring is then discarded, and a new ring is inserted.
  • Anavera (Segesterone Acetate / Ethinyl Estradiol):
    • A reusable $1\text{-year}$ vaginal ring.
    • Used on a $3\text{-weeks}\text{ in, }1\text{-week}\text{ out}$ schedule for up to $13$ cycles ($1$ year).
    • Between uses during the $1\text{-week}$ withdrawal period, the ring is washed with mild soap and warm water and stored at room temperature.
    • Less extensively evaluated in individuals with a Body Mass Index ($BMI$) $>29\,kg/m^2$, where contraceptive efficacy may be decreased.
  • Pros: Highly effective, continuous systemic delivery, private, does not require daily action.
  • Cons: Patient discomfort with intravaginal self-insertion, anxiety regarding foreign body displacement, or concern regarding interference during sexual intercourse (though designed to remain in place during coitus).
• Transdermal Contraceptive Patch (Ethinyl Estradiol / Norelgestromin):
  • Mechanism & Pharmacokinetics: A transdermal patch applied to the skin (buttocks, abdomen, upper outer arm, or upper torso) delivering continuous systemic levels of ethinyl estradiol and norelgestromin.
  • Standard Regimen: Applied weekly for $3$ consecutive weeks ($1$ patch per week), followed by $1$ patch-free week to permit withdrawal bleeding.
  • Systemic Estrogen Exposure: The norelgestromin transdermal patch delivers a higher mean steady-state concentration and area under the curve ($AUC$) of estrogen compared to a 35\,\null\mu g ethinyl estradiol oral pill, resulting in a slightly higher relative risk of venous thromboembolism relative to low-dose oral contraceptives.
  • Pros: Highly effective, continuous delivery, requires attention only once per week.
  • Cons: Localized cutaneous site reactions, risk of patch detachment due to exercise, friction, or excessive diaphoresis.

Adverse Effects, Risks, and Contraindications of CHCs

• Venous Thromboembolism ($VTE$) Risk Profile:
  • Estrogen stimulates the hepatic synthesis of clotting factors $II$, $VII$, $VIII$, $XII$, and fibrinogen, generating a mild prothrombotic state.
  • Baseline Rates and Comparative Incidence:
    • Non-pregnant, non-user baseline: $1\text{ to }2$ cases per $10{,}000\text{ woman-years}$.
    • Combined hormonal contraceptive users: $2\text{ to }4$ cases per $10{,}000\text{ woman-years}$ (approx. a $2.0\times\text{ to }2.2\times$ baseline relative risk).
    • Pregnant women: $16\text{ to }20$ cases per $10{,}000\text{ woman-years}$ (approx. a $16\times$ baseline relative risk).
    • Postpartum women (first $6$ weeks): $30\text{ to }76$ cases per $10{,}000\text{ woman-years}$ (approx. a $30\times\text{ to }76\times$ baseline relative risk).
  • Estrogen-containing contraceptives are absolutely contraindicated during the first $6$ weeks postpartum due to this extreme baseline hypercoagulability.
• Cardiovascular and Cerebrovascular Risks:
  • Minimal direct baseline blood pressure elevation occurs with CHCs in healthy individuals.
  • Significant elevation in the risk of Myocardial Infarction ($MI$) and ischemic stroke occurs in specific high-risk populations:
    • Cigarette smokers aged $\ge 35\text{ years}$.
    • Individuals with severe or uncontrolled hypertension.
    • Patients with migraine headaches with aura (exhibiting up to a $3\times$ increased baseline risk of stroke and $MI$).
• Hepatic and Biliary Complications:
  • Combined hormonal contraceptives impair biliary transport and gallbladder contractility; thus, they are contraindicated in patients with active, symptomatic gallbladder disease.
  • Contraindicated in severe, decompensated cirrhosis, hepatocellular adenomas, and malignant hepatomas.
• Pharmacokinetic Drug Interactions:
  • Hepatic Enzyme Inducers: Co-administration of microsomal enzyme-inducing medications (e.g., antiepileptics such as phenytoin, carbamazepine, phenobarbital, topiramate, and rifampin) accelerates hepatic metabolism of both estrogen and progestin, significantly lowering serum hormone concentrations and reducing contraceptive efficacy.
  • Lamotrigine: Ethinyl estradiol induces the glucuronidation of lamotrigine, significantly increasing its clearance, dropping plasma lamotrigine levels, and placing patients at elevated risk for breakthrough seizures.
• Oncologic Risks and Protective Effects:
  • Breast Cancer: Active use of CHCs is associated with a minor, statistically small relative risk ($RR \approx 1.2$) of breast cancer diagnosis. This risk declines back to baseline levels $10\text{ years}$ after discontinuation of the hormone.
  • Endometrial Cancer: CHC use provides a profound protective effect, reducing the risk of endometrial cancer by approximately $40\%$.
  • Ovarian Cancer: CHC use reduces the risk of epithelial ovarian cancer by approximately $50\%$ after $10\text{ years}$ of continuous use.
  • Cervical Cancer: A slight increase in cervical cancer risk is observed with long-term use ($>5\text{ years}$), which returns to baseline $10\text{ years}$ post-cessation. This association may be confounded by higher rates of Human Papillomavirus ($HPV$) exposure.
• Absolute Contraindications (US Medical Eligibility Criteria Category 4):
  • Age $\ge 35\text{ years}$ and smoking $\ge 15\text{ cigarettes/day}$.
  • Multiple risk factors for arterial cardiovascular disease (e.g., advanced age, smoking, diabetes, severe hypertension).
  • Uncontrolled or severe hypertension (systolic $\ge 160\text{ }mmHg$ or diastolic $\ge 100\text{ }mmHg$).
  • Current or history of Deep Vein Thrombosis ($DVT$) or Pulmonary Embolism ($PE$).
  • Known thrombogenic mutations (e.g., Factor V Leiden, Prothrombin G20210A).
  • History of ischemic heart disease, stroke, or complicated valvular heart disease.
  • Migraine with aura at any age.
  • Current or past history of breast cancer (hormone-sensitive malignancy).
  • Systemic Lupus Erythematosus ($SLE$) with positive or unknown antiphospholipid antibodies.
  • Diabetes mellitus with duration $>20\text{ years}$ or with nephropathy, retinopathy, neuropathy, or vascular disease.
  • Severe (decompensated) cirrhosis, hepatocellular adenoma, or hepatoma.
  • Symptomatic gallbladder disease.
  • Postpartum status $< 6\text{ weeks}$.

Progestin-Only Contraceptive Methods

• General Indications:
  • Progestin-only methods avoid the thrombogenic and cardiovascular risks associated with synthetic estrogen.
  • Indicated for patients with contraindications to estrogen, including history of $VTE$, severe hypertension, age $\ge 35\text{ years}$ who smoke, postpartum status $< 6\text{ weeks}$, or breastfeeding status.
• Progestin-Only Pills (POPs / "Mini-Pills"):
  • Over-the-Counter POP (Opill / Norethindrone $0.35\text{ }mg$):
    • Available over-the-counter for approximately $\$50$ per pack.
    • Typical use failure rate is approximately $5\%$.
    • Primary Mechanism of Action: Thickens cervical mucus to inhibit sperm transit and induces endometrial atrophy. Low-dose POPs do not consistently suppress ovulation (suppressing ovulation in only $\sim 40\%$ of menstrual cycles).
    • Administration Requirements: Must be taken continuously without hormone-free intervals. Requires extremely strict daily compliance within a $3\text{-hour}$ window. If taken $>3\text{ hours}$ late, cervical mucus quickly thins, requiring back-up contraception for $48\text{ hours}$.
    • Main drawback is frequent unscheduled breakthrough bleeding and cycle irregularity.
  • Drospirenone POP (Slynd / $4\text{ }mg$ Drospirenone):
    • A higher-dose prescription progestin-only pill.
    • Primary Mechanism of Action: Reliably suppresses ovulation in addition to thickening cervical mucus and causing endometrial atrophy.
    • Efficacy approaches that of combined oral contraceptives.
• Depot Medroxyprogesterone Acetate (DMPA / Depo-Provera):
  • Dosing and Route: $150\text{ }mg$ intramuscular ($IM$) injection administered once every $12\text{ weeks}$ ($3\text{ months}$).
  • Mechanism of Action: High systemic progestin levels completely suppress the pre-ovulatory $LH$ surge, reliably inhibiting ovulation. Also induces endometrial atrophy and cervical mucus thickening.
  • Pros: Requires dosing only four times per year, eliminating daily compliance demands.
  • Cons & Side Effects:
    • Weight Gain: Associated with significant variable weight gain, particularly in young or obese adolescent populations.
    • Delayed Return of Fertility: Ovulatory clearance and fertility restoration may be delayed for $10\text{ to }18\text{ months}$ after the last injection.
    • Bone Mineral Density ($BMD$) Loss: Suppresses ovarian estradiol production, leading to hypoestrogenism and reversible loss of bone mineral density. Prolonged continuous use beyond $2\text{ years}$ requires clinical evaluation of risks and benefits.
• Subdermal Etonogestrel Implant (Nexplanon):
  • Description: A single flexible radiopaque rod containing $68\text{ }mg$ etonogestrel inserted subdermally into the inner aspect of the upper non-dominant arm. Duration of action is $3\text{ years}$.
  • Efficacy: The most effective reversible contraceptive method available ($<0.05\%$ failure rate), demonstrating efficacy superior to surgical tubal ligation.
  • Mechanism of Action: Complete suppression of ovulation, profound thickening of cervical mucus, and endometrial atrophy.
  • Pros: $3\text{ years}$ of continuous protection without requiring daily, weekly, or monthly user adherence.
  • Cons & Discontinuation:
    • Requires a minor outpatient subdermal insertion and removal procedure under local anesthesia.
    • Irregular Bleeding Profile: Unscheduled bleeding is the single most common reason for premature removal. Approximately $\frac{1}{3}$ of users experience amenorrhea or infrequent bleeding, $\frac{1}{3}$ experience normal frequency bleeding, and $\sim 29\%$ experience prolonged or frequent unscheduled bleeding.

Emergency Contraception (EC)

• Levonorgestrel (Plan B One-Step, My Choice):
  • Dose & Availability: Single $1.5\text{ }mg$ oral dose available over-the-counter without age or prescription restrictions.
  • Mechanism of Action: Inhibits or delays the pre-ovulatory Luteinizing Hormone ($LH$) surge, thereby delaying ovulation to allow surviving sperm to die in the female reproductive tract.
  • Ineffective if the pre-ovulatory $LH$ surge has already occurred or if ovulation has taken place prior to ingestion. Does not disrupt an established implantation or pregnancy.
  • Timing & Efficacy: Must be ingested within $72\text{ hours}$ ($3\text{ days}$) of unprotected intercourse (with diminished efficacy up to $120\text{ hours}$). Reduces baseline pregnancy risk by approximately $75\%$.
  • Efficacy is significantly reduced in individuals with elevated Body Mass Index ($BMI \ge 25\text{ or }30\text{ }kg/m^2$).
• Ulipristal Acetate (Ella):
  • Dose & Availability: Single $30\text{ }mg$ oral dose; requires a prescription.
  • Mechanism of Action: A Selective Progesterone Receptor Modulator ($SPRM$). Directly inhibits or postpones follicular rupture/ovulation even after the $LH$ surge has already begun. Also alters endometrial receptivity.
  • Timing & Efficacy: Highly effective when taken up to $120\text{ hours}$ ($5\text{ days}$) after unprotected coitus. Reduces pregnancy risk by approximately $98\%$. Superior to levonorgestrel, particularly in overweight and obese individuals.
• Yuzpe Regimen (Combined Oral Pill Emergency Contraception):
  • Dose: Ingestion of multiple standard combined oral contraceptive pills yielding 100\text{ }\null\mu g ethinyl estradiol and $0.5\text{ }mg$ levonorgestrel per dose, repeated $12\text{ hours}$ later.
  • Cons: High incidence of severe nausea and vomiting (requiring antiemetic pre-medication). Less effective than levonorgestrel or ulipristal acetate, but serves as a salvage option when dedicated EC products are unavailable.
• Copper Intrauterine Device (Copper IUD / ParaGard):
  • Timing & Administration: Placed intravaginally/intrauterinely within $5\text{ days}$ ($120\text{ hours}$) following unprotected intercourse.
  • Mechanism of Action: Continuous release of copper ions induces a sterile localized inflammatory reaction within the endometrium and uterine cavity that is toxic to sperm and ova, preventing fertilization.
  • Efficacy: $>99.9\%$ effective; the most effective overall method of emergency contraception.
  • Benefit: Provides ongoing, highly effective long-term reversible contraception for up to $10\text{ to }12\text{ years}$ post-insertion.

Undesired Pregnancy and Induced Abortion

• Epidemiology and Demographics:
  • Approximately $50\%$ of all pregnancies in the United States are unintended (classified as mistimed or unwanted).
  • Approximately $1\text{ in }3$ women in the U.S. will undergo an induced abortion during their reproductive lifetime.
  • In recent national data (2023–2025), approximately $1{,}126{,}000$ abortions were provided by U.S. clinicians annually.
  • Gestational Age Breakdown:
    • $\sim 80\%$ of all induced abortions occur before $9\text{ weeks}$ of gestation.
    • $\sim 92\%$ occur at or before $13\text{ weeks}$ of gestation.
• Legalization and Public Health Context:
  • Legalization via Roe v. Wade (1973) did not significantly increase total abortion incidence (rates gradually declined over subsequent decades), but transformed procedural safety by shifting services to clinical settings.
  • Legalization reduced overall maternal mortality by eliminating high-risk, unregulated, illegal abortions.
  • Dobbs v. Jackson Women's Health Organization (2022) overruled Roe v. Wade (1973) and Planned Parenthood v. Casey (1992), returning authority to individual states to regulate or restrict abortion. Induced abortion remains legal in New York State.
  • Global Health Stats (WHO):
    • Globally, $45\%$ of all induced abortions are unsafe.
    • $33\%$ of unsafe abortions are performed by untrained individuals using dangerous, invasive methods.
    • Unsafe abortion accounts for $4.7\%\text{ to }13\%$ of global maternal deaths annually, resulting in approximately $7{,}000{,}000$ acute hospital admissions per year.
• Clinical Evaluation and Patient Counseling:
  • Informed Consent: Requires verification of decision-making capacity without external coercion.
  • New York State Regulations: Consent from the biological partner/father or parent (for minors $<18\text{ years}$ of age) is not required.
  • Options Counseling: Non-judgmental discussion regarding continuing the pregnancy (with prenatal care/parenting support), adoption options, or induced abortion. Practitioners with conscientious objections must promptly refer patients to accessible abortion providers.
  • Medical Contraindications: There are virtually no absolute medical contraindications to induced abortion, as continuing a pregnancy poses a statistically higher risk of maternal morbidity and mortality than undergoing an abortion procedure.

Protocols and Techniques for Induced Abortion

• Medical Abortion:
  • Accounts for $\ge 50\%$ of all abortions in the United States.
  • FDA-Approved Regimen (up to $10\text{ weeks}$ / $70\text{ days}$ gestational age; extended up to $11\text{ weeks}$ in clinical protocols):
    1. Mifepristone (RU-486): $200\text{ }mg$ orally. Competitive progesterone receptor antagonist. Blocks progesterone receptors in the decidua, causing breakdown of the endometrial lining, embryonic detachment, and a rapid decrease in placental $hCG$ production. Regression of the corpus luteum follows, lowering endogenous progesterone further and triggering uterine contractility and cervical softening.
    2. Misoprostol: 800\text{ }\null\mu g administered $24\text{ to }48\text{ hours}$ after mifepristone via buccal, sublingual, or vaginal routes. Synthetic Prostaglandin $E_1$ ($PGE_1$) analog. Directly stimulates uterine myometrial contractions and induces cervical ripening/dilatation to expel the detached tissue.
  • Efficacy: $97\%\text{ to }99\%$ complete abortion rate at $<7\text{ weeks}$ gestation; $95\%\text{ to }97\%$ complete abortion rate at $8\text{ to }10\text{ weeks}$ gestation.
• First-Trimester Surgical Abortion:
  • Suction Vacuum Aspiration:
    • Manual Vacuum Aspiration (MVA): Performed in an office setting using a hand-held suction syringe.
    • Electric Vacuum Aspiration (EVA): Performed using an electric suction pump in a clinic or surgical suite.
  • Involves local anesthesia (paracervical block), gentle mechanical cervical dilatation, and vacuum aspiration of uterine contents.
• Second-Trimester Surgical and Medical Abortion:
  • Dilation and Evacuation (D&E): Surgical extraction of fetal tissue. Requires extensive pre-procedure cervical preparation using osmotic dilators (e.g., Laminaria—dried seaweed tents that absorb tissue fluid and expand slowly to dilate the cervix) or misoprostol.
  • Labor Induction Abortion: High-dose misoprostol ($PGE_1$) administration to induce myometrial contractions and vaginal delivery of the fetus. May involve ultrasound-guided intra-fetal or intra-amniotic injection (e.g., potassium chloride or digoxin) to induce fetal demise prior to labor induction.
• Complications and Evidence-Based Controversies:
  • Complications: Very low overall complication rate. Potential risks include heavy hemorrhage, Retained Products of Conception (RPOC—slightly higher incidence following medical abortion vs. surgical abortion), endometritis/infection, and uterine perforation (surgical procedures only, extremely rare in the first trimester).
  • Debunked Myths: Scientific studies confirm that safe, legal induced abortion does not increase the risk of subsequent infertility, ectopic pregnancy, preterm labor, cervical insufficiency, breast cancer, or clinical depression.