While many people focus solely on RU 486, the so-called " French abortion pill," the RU 486 technique actually uses two powerful synthetic hormones with the generic names of mifepristone and misoprostol  to chemically induce abortions in women five-to-nine weeks pregnant.
The RU 486 procedure requires at least three trips to the abortion facility. In the first visit, the woman is given a physical exam, and if she has no obvious contra-indications ("red flags" such as smoking, asthma, high blood pressure, obesity, etc., that could make the drug deadly to her ), she swallows the RU 486 pills. RU 486 blocks the action of progesterone, the natural hormone vital to maintaining the rich nutrient lining of the uterus. The developing baby starves as the nutrient lining disintegrates.
At a second visit 36 to 48 hours later, the woman is given a dose of artificial prostaglandins, usually misoprostol, which initiates uterine contractions and usually causes the embryonic baby to be expelled from the uterus.  Most women abort during the 4-hour waiting period at the clinic, but about 30% abort later at home, work, etc.,  as many as 5 days later. A third visit about 2 weeks later determines whether the abortion has occurred or a surgical abortion is necessary to complete the procedure (5 to 10% of all cases).
There are several serious well documented side effects associated with RU 486/prostaglandin abortions, including prolonged (up to 44 days)  and severe bleeding, nausea, vomiting,  pain,  and even death. At least one woman in France died while others there suffered life-threatening heart attacks from the technique.  In U.S. trials conducted in 1995, one woman is known to have nearly died after losing half her blood and requiring emergency surgery. 
Long term effects of the drug have not yet been sufficiently studied, but there are reasons to believe that RU 486 could affect not only a woman’s current pregnancy, but her future pregnancies as well, potentially inducing miscarriages or causing severe malformations in later children. 
(NOTE: Some women have changed their minds and successfully continued their pregnancies and given birth to healthy babies after taking just the first pill (mifepristone). You may be able to reverse this type of abortion. For more information contact your OB/GYN or you may contact this hotline 24/7: 877-558-0333 www.abortionpillreversal.com)
The procedure with methotrexate is similar to the one using RU 486, though administered by an intramuscular injection instead of a pill. 
Originally designed to attack fast growing cells such as cancers by neutralizing the B vitamin folic acid necessary for cell division, methotrexate apparently attacks the fast growing cells of the trophoblast as well, the tissue surronding the embryo that eventually gives rise to the placenta. The trophoblast not only functions as the "life support system" for the developing child,  drawing oxygen and nutrients from the mother’s blood supply and disposing of carbon dioxide and waste products,  but also produces the hCG (human chorionic gonadotropin) hormone which signals the corpus luteum to continue the production of progesterone necessary to prevent breakdown of the uterine lining and loss of the pregnancy.  Methotrexate initiaties the disintengration of that sustaining, protective, and nourishing environment. Deprived of the food, oxygen, and fluids he or she needs to survive, the baby dies.
Three to seven days later (depending on the protocol used), a suppository of misoprostol (the same prostaglandin used with RU 486) is inserted into a woman’s vagina to trigger expulsion of the tiny body of the child from the woman’s uterus. Sometimes this occurs within the next few hours, but often a second dose of the prostaglandin is required, making the time lapse between the initial administration of methotrexate and the actual completion of the abortion as long as several weeks.  A woman may bleed for weeks (42 days in one study ), even heavily,  and may abort anywhere -- at home, on the bus, at work, etc.  Those found to be still pregnant in later visits (at least 1 in 25) are given surgical abortions. 
Even doctors who support abortion are reluctant to prescribe methotrexate for abortion because of its high toxicity and unpredictable side effects.  Those side effects commonly include nausea, pain, diarrhea,  as well as less visible but more serious effects such as bone marrow depression, severe anemia, liver damage and methotrexate-induced lung disease. 
The manufacturer warns in the package insert that while methotrexate has shown itself useful in treating certain types of cancer and severe cases of arthritis and psoriasis, "deaths have been reported with the use of methotrexate," and recommends that its use be limited to "physicians whose knowledge and experience includes the use of antimetabolite therapy."  Though researchers performing methotrexate abortions have dismissed such concerns because of the low dosage used,  other doctors in the abortion trade have disagreed,  and the package insert clearly warns that "toxic effects may be related in frequency and severity to dose or frequency of administration but have been seen at all doses" (emphasis added). 
Second & Third Trimester
These methods involve the injection of drugs or chemicals through the abdomen or cervix into the amniotic sac to cause the death of the child and his or her expulsion from the uterus. Several drugs have been tried,  but the most commonly used are hypertonic saline, urea, and prostaglandins.
Otherwise known as "saline amniocentesis," "salting out," or a "hypertonic saline" abortion, this technique is used after 16 weeks of pregnancy, when enough fluid has accumulated in the amniotic fluid sac surrounding the baby.
A needle is inserted through the mother’s abdomen and 50-250 ml (as much as a cup) of amniotic fluid is withdrawn and replaced with a solution of concentrated salt.  The baby breathes in, swallowing the salt, and is poisoned. The chemical solution also causes painful burning and deterioration of the baby’s skin.  Usually, after about an hour, the child dies. The mother goes into labor about 33 to 35 hours after instillation and delivers a dead, burned, and shriveled baby.  About 97% of mothers deliver their dead babies within 72 hours.
Hypertonic saline may initiate a condition in the mother called "consumption coagulopathy" (uncontrolled blood clotting throughout the body) with severe hemorrhage as well as other serious side effects on the central nervous system.  Seizures, coma, or death may also result from saline inadvertently injected into the woman’s vascular system.
Because of the dangers associated with saline methods, other instillation methods such as hypersomolar urea are sometimes employed,  though these are less effective and usually must be supplemented by oxytocin or a prostaglandin in order to achieve the desired result.  Incomplete or failed abortion remains a problem with urea methods, often precipitating the additional risk of surgery.
As with other instillation techniques, gastrointestinal side effects such as nausea or vomiting are frequent, but the most common problem with second trimester techniques is cervical injuries, which range from small lacerations to complete detachments of the anterior or posterior cervix. Between 1% and 2% of patients using urea must be hospitalized for treatment of endometritis, an infection of the lining oft he uterus.
Prostaglandins are naturally produced chemical compounds which normally assist in the birthing process. The injection of concentrations of artificial prostaglandins prematurely into the amniotic sac induces violent labor and the birth of a child usually too young to survive. Often salt or another toxin is first injected to ensure that the baby will be delivered dead,  since some babies have survived the trauma of a prostaglandin birth and been born alive.  This method is used during the second trimester. 
In addition to risks of retained placenta, cervical trauma, infection, hemorrhage,  hyperthermia, bronchoconstriction, tachycardia,  more serious side effects and complications from the use of artificial prostaglandins, including cardiac arrest and rupture of the uterus, can be unpredictable and very severe. Death is not unheard of. 
18. Étienne-Émile Baulieu, M.D., Ph. D., "1993: RU 486 -- A Decade on Today and Tomorrow," in Clinical Applications of Mifepristone (RU 486) and Other Antiprogestins, Institute of Medicine, eds. Molla .S. Donaldson et al (Washington, D.C.: National Academy Press, 1993), p. 92-96. Though Baulieu, creator of the abortion pill, recommends its use up to nine weeks, American trials have found the method considerably less effective after the seventh week, according to Carol Jouzaiis, "Abortion Pill Clinic Tests Drawing to a Close in U.S.," Chicago Tribune, Wednesday, August 30, 1995, p. 1.
19. The Population Council of New York, Release, October 27, 1994, p. 3. The Population Council is the entity conducting tests on RU 486 in the United States. The regimen in France, where the drug was first developed and approved, involves a total of four visits, adding an additional week for reflection prior to the ingestion of the pills (Diane Gianelli, "RU 486 effective, not problem-free," American Medical News, April 12, 1993, p. 25.
20. See Janice G. Raymond, Renate Klein, Lynette J. Dumble, RU 486: Misconceptions, Myths, and Morals (Cambridge, MA: Institute on Women and Technology, 1991), pp. 17, 34, 35; and Beatrice Couzinet, M.D., et al, "Termination of Early Pregnancy by the Progesterone Antagonist RU 486 (Mifepristone)," New England Journal of Medicine Vol. 315 (December 18, 1986), p. 1565; Louise Silvestre, M.D., et al, "Voluntary Interruption of Pregnancy with Mifepristone (RU 486) and a Prostaglandin Analogue," New England Journal of Medicine, Vol. 322 (March 8, 1990), p. 645.
21. Raymond, Klein, and Dumble, Misconceptions, cited in note 20, pp. 57-62.
22. André Ulmann, et al, "Medical Termination of Early Pregnancy With Mifepristone (RU 486) Followed By A Prostaglandin Analogue," Acta Obst. Gyn. Scand., Vol. 71 (1992), pp. 280-281.
23. Population Council, Release, cited in note 19, p. 3
24. Gianelli, "RU 486 effective..." cited in note 19, p. 25.
25. Élisabeth Aubeny and É.É.Baulieu, "Contragestion with Ru 486 and an orally active prostaglandin," C.R. Acad. Sci. Paris (III), Vol. 312 (1991), pp. 539-545, obtained a 95% completion rate with women 49 days amenorrhea or less. Carolyn McKinley, et al, "The effect of dose of mifepristone and gestation on the efficacy of medical abortion with mifepristone and misoprostol," Hum. Reproduc., Vol. 8 (1993), pp. 1502-1503, obtained a completion rate of 89.1% for women 50-63 days amenorrhea.
26. Mary W. Rodger and David T. Baird, "Blood loss following a prostaglandin analogue (Gemeprost)" Contraception, Vol. 40 (1989), pp. 439-447.
27. UK Multicentre Trial, "The efficacy and tolerance of mifepristone and prostaglandin in first trimester termination of pregnancy, B.J. Obst. & Gyn., Vol. 97 (1990), pp. 480-486.
28. Population Council, Release, cited in note 19, p. 3.
29. McKinley, et al, "The effect of dose of mifepristone...," cited in note 25, p. 1504.
30. Alan Riding, "Frenchwoman’s Death is Linked To Abortion Pill and a Hormone," New York Times, April 10, 1991, p. A-10
31. Mark Louviere, M.D., "Group lied when it said ‘abortion pill’ test resulted in no complications,’ Waterloo Courier, September 24, 1995, p. F3. See alsoTom Carney, "‘Abortion pill’ test goes awry for one patient,"Des Moines Register, September 21, 1995, pp. 1M, 5M.
32. Raymond, Klein, and Dumble, Misconceptions, cited in note 20 , pp. 71-79.
33. Richard U. Hausknecht, M.D., "Methotrexate and Misoprostol to Terminate Early Pregnancy," New England Journal of Medicine, Vol. 33, No. 9 (August 31, 1995), p.538, and Eric A Schaff, M.D., et al, "Combined Methtrexate and Misoprostol for Early Induced Abortion," Archives of Family Medicine, Vol. 4. 1995, p. 2.
34. Mitchell D. Creinin, M.D., "Methotrexate for abortion at £42 days gestation," Contraception, Vol. 48, No. 6 (December, 1993), p. 519.
35. Daniel R. Mishell, Jr., M.D., and Val Davajan, M.D., Infertility, Contraception, & Reproductive Endochrinology, 2nd Ed. (Oradell, NJ: Medical Economics Books, 1986), pp. 120.
36. Keith Moore, Ph.D., Essentials of Human Embryology (Philadelphia: B.C. Decker, Inc., 1988), p. 10.
37. Mishell and Davajan, cited in note 35, p. 120.
38. Schaff, et al, cited in note 33, p. 4. The precise time of abortion is hard to specify; while Schaff measured decrease in ßhCG levels as an indicator of abortion, Hausknecht (cited in note 33) looked for the "expulsion of the products of conception" or the "passage of tissue" (P. 538). Using this criteria, Hausknecht still apparently had some who took at least 18 days to abort (methotrexate on day 1, misoprostol day 7, repeat misoprostol, day 14, abortion 4 days later, pp. 538-539). Those still pregnant at that point underwent a surgical abortion.
39. Mitchell D. Creinin, M.D., and Philip D. Darney, M.D., "Methotrexate and misoprostol for early abortion," Contraception, Vol. 48 (October, 1993), p. 344.
40. See Schaff, et al, cited in note 33, p. 4., Hausknecht, cited in same note, pp. 538-539.
41. Conversation between Richard U. Hausknecht, M.D., and Phil Donahue, "An Abortion Pill by Prescription Without Surgery," The Phil Donahue Show, September 26, 1995; Journal Graphics, Transcript #4346, pp. 2-4.
42. Schaff, et al, cited in note 33, p. 2. See also Hausknecht, cited in note 33, p. 538.
43. According to an October 22,1993 article titled "Existing Drugs Induced Abortions But some warn about toxicity," appearing on p. 7 of Newsday (New York), the medical director of Planned Parenthood of New York, Dr. Hakim Elahi indicated the side effects were so unpredictable he would not use it as an abortion drug in any dose. In a letter to the editors of the New York Times (April 8, 1996, at p. A14), abortionist Don Sloan warned that methotrexate can produce severe anemias, ulcers, and bone marrow depressions that can be fatal,even at the doses used for abortion and said "many of us in the ‘abortion trade,’ as I am, are recoiling at the stark irresponsibility of those who are parading this medication in such cavalier fashion."
44. Schaff, et al, cited in note 33, p. 4.
45. Physicians’ Desk Reference (PDR), 47th edition (Montvale, NJ: Medical Economics Data, 1993)., p. 1245.
46. PDR, cited above.
47. Richard Hausknecht, interviewed by Charlayne Hunter-Gault, MacNeil-Lehrer News Hour, PBS, August 30, 1995.
48. See Drs. Hakim Elahi and Don Sloan, cited in note 43.
49. PDR, ctied in note 45, p. 1246.
52. Nelson B. Isada, MD., et al, mention potassium chloride and digoxin in "Fetal Intracardiac Potassium Chloride Injection to Avoid the Hopeless Resuscitation of an Abnormal Abortus: I. Clinical Issues," Obstetrics and Gynecology, Vol. 80, No. 2 (August 1992), pp.296, 298, (though they administered this directly into the baby’s heart, rather than just the surrounding amniotic sac), and Marc A. Bygdeman mentions, but does not discuss in detail, the use of hypertonic glucose in "Prostaglandin Procedures," Second Trimester Abortion, ed. Gary S. Berger, et al (Boston: Martinus Nijhoff Publishers, 1981), p. 101. Oxytocin, normally used to stimulate contractions in full term pregnancies, can apparently also be used as an abortifacient in mid-trimester pregnancies, if used in high enough doses, according to Stubblefield, "First and Second Trimester Abortion...,"cited in note 9, p. 1027.
53.Thomas D. Kerenyi, "Hypertonic Saline Instillation," in Second Trimester Abortion, cited above, p. 81.
54. R.S. Galen, P. Chauhan, H. Wietzner, et al, "Fetal pathology and mechanism of fetal death in saline-induced abortion: a study of 143 gestations and critical reveiw of the literature," American Journal of Obstetrics and Gynecology, Vol. 120 (1974), p.347.
55. Jeff Lyon, ‘Abortion paradox: A live baby," York Daily Record (York, Pennsylvania), August 21, 1982. See also Congressional Record, March 23, 1983, H1680.
56. Stephen L. Corson., M.D., et al, Fertility Control (Boston, MA: Little, Brown, and Company, 1985), pp. 82-83.
57. Thomas D. Kerenyi, Abortion and Sterilization, ed. Hodgson, cited in note 12, p. 362.
58. James R. Scott, M.D., et al, Danforth’s Obstetrics and Gynecology, 6th ed. (Philadephia: J.B. Lippincott, 1990), p. 726.
59. Thomas D. Kerenyi, "Hypertonic Saline Instillation," in Second Trimester Abortion, cited in note 52, p.83; and R. Bolognese and S. Corson, Interruption of Pregnancy -- A Total Patient Approach (Baltimore: Wilkins and Wilkins, 1985), p. 136.
60. Marc A. Bygdeman, "Prostaglandin Procedures," in Second Trimester Abortion, cited in note 52, p. 101.
61. Ronald T. Burkman, Theodore M. King, Milagros F. Atienza, "Hyperosmolar Urea," in Second Trimester Abortion,cited in note 52, pp. 109-110.
62. Ibid., pp. 115-116.
63 . Nancy K. Rhoden, "The New Neonatal Dilemma: Live Births from Late Abortions," The Georgetown Law Journal, Vol. 72 (1984), p. 1458.
64. Liz Jeffries and Rick Edmonds, "Abortion, The Dreaded Complication," The Philadelphia Inquirer, August 2, 1981, 4 page insert.
65. Warren M. Hern, M.D., Abortion Practice, cited in note 50, pp. 123, 125. 66. Ibid., p. 125.
66. Ibid., p. 125.
67. James R. Scott, Danforth’s Obstetrics and Gynecology, cited in note 58, p. 726.
68. Willard Cates, M.D. and H.V.F. Jordaan, "Sudden Collapse and Death of Women Obtaining Abortion Induced by Prostaglandin F2 Alpha," American Journal of Obstetrics and Gynecology, Vol. 133 (February 15, 1979), pp. 398-400. See also David Grimes, M.D., et al, "Midtrimester abortion by intra-amniotic prostaglandin F2a: Safer than saline?" Obstet Gynecol, Vol. 49 (1977), p. 612 and A.C. Wentz, et al, "Posterior cervical rupture following prostaglandin-induced midtrimester abortion," American Journal of Obstetrics and Gynecology, Vol. 115 (1973), p. 1107.
*Information provided by National Right to Life Committee website.