In the U.S., the most common protocols are two variations on the French Protocol called the Population Council, or PC, Protocol and the Abortion Rights Movement, or ARM, Protocol. These are named for two large-scale studies of medical abortion that were done in the United States. A key benefit of these protocols is that they can be done very early in pregnancy. The seventh week is up to the 49 th day after the first day of the last menstrual period. It has also been used in treating other diseases, including rheumatoid arthritis and psoriasis.
Methotrexate works by interfering with the development of rapidly dividing cells in the human body.
In 1982, researchers discovered that methotrexate was an effective treatment for ectopic pregnancy. Ectopic pregnancy is a dangerous condition in which a fertilized human egg implants in the wrong place, usually in one of the two fallopian tubes that transport eggs from the ovaries to the uterus. While an ectopic pregnancy cannot produce a baby, it can threaten the health, fertility and even the life of the woman. Before methetrexate, the only treatment for an ectopic pregnancy was surgery. The surgery, unfortunately, often results in fertility problems because the fallopian tube, sometimes also an ovary or, in the worst cases, the entire uterus may need to be removed.