Combined Hormonal Contraception

Summary

Combined hormonal contraceptives (pills, patch, ring) are highly effective, reversible methods that mainly work by suppressing ovulation. They regulate cycles, reduce pain and bleeding, improve acne, and lower risks of some cancers. Side effects include nausea, headaches, and rare serious risks like blood clots and stroke. They are contraindicated in smokers over 35, migraine with aura, thromboembolic disease, severe liver disease, and breast cancer, and do not protect against STIs.

Overview

Combined hormonal contraceptives (CHCs) contain both estrogen and progestin and are among the most effective reversible methods for preventing pregnancy when used correctly. They are available in several forms, including combined oral contraceptive pills (COCs), the transdermal patch, and the vaginal ring. In addition to contraception, CHCs provide numerous noncontraceptive benefits, including regulation of menstrual cycles, reduction of menstrual pain and flow, and management of certain gynecological and endocrine disorders.

Mechanism of Action

CHCs work primarily by inhibiting ovulation through suppression of the hypothalamic–pituitary–ovarian axis. Estrogen and progestin provide negative feedback on gonadotropin release, preventing the mid-cycle luteinizing hormone LH surge. Progestin also thickens cervical mucus, creating a barrier to sperm penetration, and induces endometrial changes that are unfavorable for implantation. Withdrawal bleeding occurs during the hormone-free interval due to a fall in circulating hormone levels and subsequent endometrial shedding.

Formulations and Regimens

1. Combined Oral Contraceptive Pills (COCPs)

• Standard OCPs: These contain both an estrogen and a progestin. They are administered most commonly in one of two ways: Daily with 21 days on and 7 days off OR daily 24 days on and 4 days off, When “off” the hormones, withdrawal bleeding will occur.

• Special formulations: Drospirenone/ethinyl estradiol (e.g., YAZ) may reduce premenstrual dysphoric disorder (PMDD) symptoms by up to 50%, The dosing is 24 days of active pills then 4 days of placebo, rather than the traditional 21 days, followed by 7 days of placebo.
  
  

2. Transdermal Contraceptive Patch

• A 5 cm × 5 cm patch (e.g., Ortho Evra®) delivering estrogen and progestin transdermally.

• Applied weekly for 3 consecutive weeks followed by 1 patch-free week.

• Provides relatively stable serum hormone levels but results in approximately 60% higher estrogen exposure compared with oral pills.
  
  

3. Vaginal Ring

• A flexible device (e.g., NuvaRing®) releasing etonogestrel and ethinylestradiol.

• Worn intravaginally for 3 weeks, removed for 1 week to allow withdrawal bleeding.

• Offers consistent hormone release and avoids gastrointestinal metabolism.
  
  

Effectiveness

• Perfect use failure rate: 0.3%

• Typical use failure rate: 9%
  Efficacy depends heavily on adherence, especially for COCs.

Noncontraceptive Benefits

• Regulation of menstrual cycles and reduction of dysmenorrhea

• Decreased menstrual blood loss

• Improvement of acne and hirsutism (due to anti-androgenic effects of some progestins)

• Reduced risk of endometrial, ovarian, and colorectal cancers

• Treatment of conditions such as polycystic ovary syndrome (PCOS), endometriosis, menstrual migraines without aura, PMDD, and functional ovarian cysts

Adverse Effects

Common: Headaches, breast tenderness, nausea, mood changes, breakthrough bleeding (particularly in the first few cycles)
Serious but rare: Venous thromboembolism (VTE), myocardial infarction, ischemic stroke, hepatocellular adenoma

Contraindications

Absolute contraindications: 

• <6 weeks postpartum. 

• Heavy smoking (>15 cigarettes/day) after age 35 

• Stage 2 hypertension

• History of VTE.

• Ischemic heart disease, stroke, complicated valvular heart disease, or migraine with aura.

• Current breast cancer 

• Severe liver disease, or diabetes with vascular complications.

Relative contraindications: 

• Mild smoking after 35.

• Controlled hypertension.

• Migraine without aura after 35.

• Gallbladder disease, mild liver disease, or cholestasis with prior COC use.

• Drug interactions affecting metabolism.