13. ORAL CONTRACEPTIVES

Oral contraceptives (OCs) are medicines used to prevent pregnancy. They work mainly by stopping ovulation, thickening cervical mucus (to block sperm), and making the uterine lining unsuitable for implantation. They do not treat a disease — they are medications taken for pregnancy prevention.

The Menstrual Cycle (Simple Overview)

A typical menstrual cycle lasts about 28 days (can range from 21–40 days). Day 1 is the first day of bleeding. Around day 14, ovulation occurs — the ovary releases an egg. The first part of the cycle is the follicular phase, controlled by FSH, which helps follicles grow. A surge of LH from the pituitary gland triggers ovulation. After ovulation, the luteal phase begins, during which the corpus luteum produces estrogen and progesterone. If pregnancy does not occur, hormone levels drop and the next cycle begins.

Pharmacotherapy Focus: Oral Contraceptive Pills (OCPs)

Only oral forms are covered here — not injectable or implantable contraceptives.

Combined Hormonal Contraceptives (CHCs)

CHCs contain both estrogen and progestin. Before prescribing them, a complete medical history and blood pressure check are essential.

Non-Contraceptive Benefits

  • Less menstrual pain and bleeding
  • More regular cycles
  • Reduced risk of anemia
  • Lower risk of ovarian and endometrial cancer
  • Reduced risk of ovarian cysts and PID
  • Reduction in acne for some users

Important Safety Note

CHCs DO NOT protect against sexually transmitted diseases — condom use is still needed.

Special Use Considerations

Women Over 35 Years

  • Low-dose estrogen CHCs (<50 mcg) can be used in healthy, non-smoking women.
  • CHCs should be avoided in women >35 years who smoke, have migraines, uncontrolled hypertension, or diabetes with complications.

Women Who Smoke

Smoking increases the risk of heart attack when combined with CHCs. Women over 35 who smoke should not use CHCs. Progestin-only pills are safer options for them.

Hypertension

  • CHCs may slightly increase BP (6–8 mmHg).
  • Allowed for women <35 years with controlled BP.
  • Contraindicated if BP ≥160/100 mmHg or end-organ damage.

Diabetes

  • Low-dose CHCs are safe for women <35 years without vascular disease.
  • Not recommended in diabetics with kidney, eye, nerve damage, or disease duration >20 years.

Dyslipidemia

  • Most low-dose CHCs do not significantly affect lipid levels.
  • Avoid CHCs in uncontrolled dyslipidemia (high LDL, high TG, low HDL) with other cardiac risk factors.

Thromboembolism Risk

  • Estrogen increases risk of blood clots in some women.
  • Risk higher with obesity, smoking, prolonged immobility, and certain progestins (desogestrel, drospirenone, norgestimate).
  • Patches and vaginal rings increase estrogen exposure → higher clot risk.
  • Progestin-only pills preferred for high-risk women.

Migraine

  • CHCs may worsen or improve migraines.
  • Women with migraine WITH aura should avoid CHCs.
  • Women who develop migraines while on CHCs should stop immediately.

Breast Cancer

Women with previous or current breast cancer should not use CHCs.

SLE (Lupus)

  • Safe in stable SLE WITHOUT antiphospholipid antibodies.
  • Avoid CHCs in SLE with vascular complications or positive antibodies.

Obesity

  • OCs may be less effective in obese women.
  • Obese women >35 years have higher clot risk — progestin-only preferred.

General Considerations for OCs

  • Perfect use: >99% effective.
  • Typical use: failure rate up to 8%.
  • Monophasic pills: same dose estrogen+progestin for 21 days.
  • Biphasic/triphasic pills: hormone levels vary.
  • Extended-cycle: 84 active pills + 7 placebo → four periods a year.
  • Continuous pills: taken every day → minimal or no periods.

Progestin-Only Pills (“Mini Pills”)

  • Less effective than CHCs.
  • Must be taken at the same time daily.
  • Higher chance of irregular bleeding and ectopic pregnancy.

Starting Oral Contraceptives

  • Quick start: begin pill same day after negative pregnancy test.
  • First-day start: begin on day 1 of next period.
  • Sunday start: first Sunday after period begins.

Managing Side Effects

Symptoms such as spotting, nausea, or bloating usually improve after 2–3 cycles.

Stop CHCs immediately if ACHES occur:

  • A – Abdominal pain
  • C – Chest pain
  • H – Headache (severe)
  • E – Eye problems
  • S – Severe leg pain

Drug Interactions

  • Rifampin reduces OC effectiveness → use backup contraception.
  • Antibiotics may rarely reduce effectiveness — use backup if breakthrough bleeding occurs.
  • Anticonvulsants (phenytoin, carbamazepine, phenobarbital) reduce OC levels — consider IUD or non-hormonal methods.

Discontinuation & Return of Fertility

Most women regain normal fertility after stopping OCs. Many can conceive in the first cycle after stopping.

Detailed Notes:

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