There are numerous birth control pill choices. According to RxList.com, oral contraceptives contain some form of synthetic female hormones estrogen and progesterone. Synthetic progesterone is called progestin. Each manufacturer may have a different blend. The pill can be progestin or estrogen only, or a combination. Some manufacturers have created different pills that have varying levels of hormones. The benefit of manufacturing pills with different combinations of ingredients is to allow women plenty of options. Some women may be more sensitive to specific hormones or be able to tolerate hormones only up to a certain level.
According to RxList.com, each brand has a unique name for the progestin compound. Essentially, the ingredient is synthetic progesterone. In addition to preventing pregnancy, progestin changes the menstrual cycle. As progestin levels drop, the uterine lining begins shedding. This signals the end of the menstrual cycle and naturally occurs if an egg has not been fertilized. When used in a birth control pill, progestin makes it difficult for sperm to make their way to the egg to fertilize it because the mucus within a woman's cervix is thickened when progestin levels are high. Progestin-only pills can be used by nursing mothers to prevent pregnancy. According to the Mayo Clinic, this "mini-pill" does not transfer from breast-milk to a baby.
Estrogen levels naturally fluctuate during a woman's monthly cycle. Once estrogen hits the peak level, ovulation begins. Ovulation refers to the releasing of an egg into the uterus. The egg can be fertilized as it travels from the ovary to the uterus via the fallopian tubes. According to the National Women's Health Resource Center, birth control pills keep estrogen at a constant level to prevent ovulation. If an egg does not erupt, a woman cannot get pregnant. Like progesterone, estrogen is manufactured synthetically and given a unique name by each manufacturer.
Besides hormones, birth control pills contain a small amount of inactive ingredients. Some brands of oral contraception have about seven inactive pills that are taken during the week of menstruation to avoid a disruption in a woman's routine. These pills do not have hormones in them and are called reminder pills. Some brands have reminder pills that contain sugar. Others may be comprised of iron. According to RxList.com, active pills contain any combination of dyes, water, corn starch, magnesium stearate, lactose, croscarmellose sodium, polyethylene glycol and titanium dioxide. These ingredients are not a comprehensive list because each brand of birth control pill will contain a different set of inactive ingredients. The purpose of these ingredients is to help maintain the form of the pill and to assist in getting the active ingredients into the body after they are swallowed. See the insert that came with the birth control pill for a comprehensive list of inactive ingredients.