Combined oral contraceptive

Combined Oral Contraceptive

The combined oral contraceptive (COC) is a type of birth control pill that contains two hormones: an estrogen and a progestin. These hormones work together to prevent ovulation, thicken cervical mucus, and thin the lining of the uterus, thereby reducing the likelihood of pregnancy.

Mechanism of Action

The primary mechanism by which COCs prevent pregnancy is the inhibition of ovulation. The estrogen component suppresses the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland, preventing the development and release of an egg from the ovary. The progestin component thickens the cervical mucus, making it more difficult for sperm to enter the uterus, and alters the endometrial lining, reducing the likelihood of implantation.

Types of Combined Oral Contraceptives

COCs are available in various formulations, differing in the type and dose of estrogen and progestin. The most common estrogen used is ethinyl estradiol, while progestins can vary widely, including norethindrone, levonorgestrel, and drospirenone.

Monophasic Pills

Monophasic COCs deliver the same dose of hormones in each active pill. This consistency can help reduce side effects and maintain stable hormone levels.

Multiphasic Pills

Multiphasic COCs vary the dose of hormones throughout the cycle. These are designed to more closely mimic the natural menstrual cycle and may reduce side effects such as breakthrough bleeding.

Benefits

COCs offer several benefits beyond contraception, including regulation of menstrual cycles, reduction in menstrual cramps, and decreased risk of ovarian and endometrial cancers. They can also improve acne and reduce symptoms of polycystic ovary syndrome (PCOS).

Risks and Side Effects

While generally safe for most women, COCs can have side effects such as nausea, breast tenderness, and mood changes. There is also a small increased risk of venous thromboembolism, particularly in women who smoke or are over 35 years old. It is important for users to discuss their medical history with a healthcare provider to determine if COCs are appropriate for them.

Contraindications

COCs are contraindicated in women with a history of deep vein thrombosis, pulmonary embolism, certain types of cancer, and uncontrolled hypertension. Women who smoke and are over 35 years old are also advised against using COCs due to increased cardiovascular risks.

Administration

COCs are typically taken once daily, at the same time each day, to maintain consistent hormone levels. Most COC packs contain 21 active pills followed by 7 placebo pills, during which withdrawal bleeding occurs. Some packs may have 24 active pills and 4 placebo pills, or even continuous active pills to eliminate withdrawal bleeding.

Also see

• Progestin-only pill
• Intrauterine device
• Contraceptive implant
• Emergency contraception

• Birth control
• Contraception
• Dictionary of birth control
• Reproductive health