It is important when discussing the Hobby Lobby case that we avoid conflating hormonal birth control methods with the medication abortion drugs. If we don't understand and emphasize that they are completely different, we are reinforcing the argument the anti sex people want to use to ban all birth control. Please follow me below the Fallopian tube for something I actually wrote a year ago when Texas passed it's draconian anti-abortion legislation. I think it is relevant now with discussion of Hobby Lobby. It seems boring and dry, but it is incredibly important from a policy standpoint that our side not buy the confusion that the other side intentionally sows. They successfully sold it to SCOTUS because the general public is confused about the drugs.
PLAN-B
aka Next Choice, or "morning after pill". This is what Hobby Lobby wants to get out of paying for. It is frequently confused with the abortion drugs, particularly mifepristone, which was essential to Hobby Lobby's argument. . The anti-abortion people stoke that confusion, and it is an important front in their attack on hormonal contraception generally. But the pharmacology as actual the opposite of the abortion drug mifepristone (see below). Instead of blocking a hormone necessary to support pregnancy, it IS that hormone (or a chemically similar one). Like other birth control pills, it fools the body into thinking it is already pregnant, so that the ovary does not release an egg. If the ovary has already released an egg, it does not work. Its failure rate exactly corresponds to the likelihood that an egg has already been released. That is why it needs to be taken as soon as possible after unprotected intercourse. It has no effect if a woman is already pregnant. If anything, it supports the pregnancy by adding even more of the pro-gestation hormone.
HORMONAL BIRTH CONTROL
Birth Control Pills/implants/Mirena IUD
These all work by making the woman's body think she is already pregnant, so she does not ovulate. May also thicken the mucus plugging the cervix, so it is harder for sperm to pass. May also thin the uterine lining, which would make it harder for a fertilized egg to implant. There is no evidence that this thinning is a significant part of the contraceptive effect, but it is the basis for the anti's claim that birth control pills cause abortions. Birth control pills are extraordinarily safe, with a risk level comparable to many over the counter drugs. If a woman gets pregnant while taking the pill, it is not considered a risk to the pregnancy. Many toddlers have ingested mom's birth control pills with no ill effects.
MIFEPRISTONE
Brand name Mifeprex. The temporary name assigned during clinical trials was RU-486. But it is not strictly correct to call it that now. It works by blocking a hormone (progesterone) that is necessary to support a pregnancy. It is the first step in a medical abortion in the US or Europe. It is EXPENSIVE! Over $80-100 per pill. When the FDA first approved it, they used a dosing regime that involved three pills. But with experience, it was found that a single pill worked just as well, and reduced the expense and side effects. One of the components of the Texas anti-abortion law, likely to be copied in other states, requires that this be given as three pills, not one. That would make the total cost of a medical abortion significantly higher than a surgical abortion, and would push more women into surgical. Mife does not have any medical uses outside of abortion, and is only approved up to 9 weeks after the last period. It works later than that, but the risk of excessive bleeding goes up.
MISOPROSTOL
Brand names Cytotec, Arthrotec among others. This is the "flea market abortion drug" talked about in Bloomberg's, because there is a robust black market for it. It is available over the counter in Mexico to treat ulcers and arthritis. It also causes uterine contractions. Obstetricians sometimes use it to "ripen" the cervix before a delivery. It does not act directly on the embryo or fetus. After mifepristone stops the development of an embryo, Cytotec is used to empty the uterus. This combo is effective 95% of the time, and it is what you would get if you went to a mainstream abortion provider in the US or Europe. Cytotec is also pretty effective (80%) used alone. It is commonly used to self induce an abortion, especially in Latin America and in Hispanic communities in the US. Whether used alone or with mifepristone, it involves 4 pills, either dissolved in the mouth or placed in the vagina. In a US clinic abortion, they are given to the patient to take at home the day after she takes mifepristone at the clinic. The Texas bill would require a trip back to he clinic to swallow the pills in front of the doctor. That creates extra expense, time, travel, etc. It also creates the risk that women would take the mifepristone at the clinic, but not return the next day for the Cytotec.
METHOTREXATE
This is an anti-cancer drug that stops development of an embryo. It is used instead of mifepristone for medical abortions in Canada. It is also used to treat tubal pregnancies. It has some other general medical uses, including rheumatoid arthritis and psoriasis. The Bloomberg article that talked about getting misoprostol at flea markets also made a reference to a black market abortion "shot". That is probably methotrexate.
There is good info about self induced abortion with Cytotec, and also about using regular birth control pills to prevent ovulation after unprotected intercourse, at the Women on the Waves website.