Oral Contraception and Combination Hormonal Methods

Oral contraceptives (birth control pills) are available only by prescription and come in either a combination of estrogen and progestin or progestin alone. Many brands of each form are available. Although both are equally effective with typical use, the combined pill is more effective with perfect use, and most women choose this form.

Some women, however, experience severe headaches or high blood pressure from the estrogen in the combined pill and must take the progestin-only pill. Not all combined pills or progestin-only pills are alike, and brands differ in the amount of estrogen or progestin they contain. Many oral contraceptive combined brands now use lower estrogen doses than previous brands and are proving to be safe and effective with fewer side effects than earlier oral contraceptives.

For all oral contraceptive users, a check-up at least once a year is essential. It is also important for women to have their blood pressure checked 3 months after beginning the pill. Former pill users who want to bear children usually regain fertility in 3 - 6 months, but they may regain it even sooner.

Hormones Used in Contraceptives

Estrogen (Estradiol)

Estrogen is the major female hormone and is responsible for female characteristics. The estrogen compound used in most oral contraceptives is estradiol, which is always used with a progestin.

Effects on Reproduction. When used throughout a menstrual cycle with progesterone, estrogen suppresses the actions of other reproductive hormones (luteinizing hormone, or LH, and follicle stimulating hormone, or FSH) and prevents ovulation.

Progesterone (Progestin)

When used in contraception, progesterone is referred to by one of several names:

• Progesterone is the name for the natural hormone.
• Progestogen is a synthetic form.
• Progestin is the term for any hormone, natural or synthetic, that causes progesterone effects; it is used as the general term in this report.

Progestins may be used alone or with estrogen in oral contraceptives. In addition, certain specific progestins are used in other kinds of contraceptives, such as etonogestrel in the Implanon implant and depo-medroxyprogesterone acetate in the injectable contraceptive Depo-Provera.

Progesterone can prevent pregnancy by itself in several ways:

• Blocking luteinizing hormone (LH), one of the reproductive hormones important in ovulation
• Maintaining a powerful barrier against the entry of sperm into the uterus by keeping the cervical mucus thick and sticky

Progestins used in contraceptives are referred to as:

• Second generation (levonorgestrel, norethisterone).
• Third generation (desogestrel, gestodene, norgestimate, drospirenone). The third-generation progestins tend to have fewer side effects. Some studies suggest, however, they may pose a slightly higher risk for blood clots than the older progestins.