I've looked into this, and to date, I haven't found any documentation that says the Birth Control Pill IS an aborticant. Everything I've read says it isn't, or it might be, but nothing conclusive.
P.S. The full quiver discussion is of personal biblical interpretation, and is not related to physical health.
I have a Davis Drug Guide for Nurses, and the contraceptives are all in one big clump. Â There is
Progressive Estrogen Oral Contraceptives: norethindrone/ethinyl acetate,
Estrostep,
Estrostep Fe , norgestrel,
Ovrette,
Contraceptive Implant: levonorgestrel,
Norplant Emergency Contraceptive: Â levonorgestrel/ethinylestradiol,
Preven, Â
Injectable Contraceptive: medroxyprogesterone,
Depo-ProveraACTION:Monophasic Oral Contraceptives:: Provide a fixed dosage of extrogen/progestin over a 21-day cycle. Â Ovulation is inhibited by suppression of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Â May alter cervical mucus and the endometrial environment, preventing penetration by sperm and implantation of the egg.
Biphasic Oral Contraceptives: Â Ovulation is inhibited by supression of FSH and LH. Â May alter cervical mucus and the endometrial environment, preventing penetration by sperm and implantation of the egg. Â In addition, smaller dose of progestin in phase 1 allows for proliferation of endometrium. Â Larger amount in phase 2 allows for adequate secretory development.
Triphasic Oral Contraceptives: Ovulation is inhibited by supression of FSH and LH. Â May alter cervical mucus and the endometrial environment, preventing penetration by sperm and implantation of the egg. Â Varying doses of estrogen/progestin may more closely mimic natural hormonal fluctuations.
Progressive Estrogen: Contains constant amount of progestin with 3 progressive doses of estrogen.
Progestin-Only Contraceptives and Contraceptive Implant: Mechanism inot clearly known.  May alter cervical mucus and the endometrial environment, preventing penetration by sperm and implantation of the egg.  Ovulation may also  be suppressed.
Medroxy-progesterone Injection: Inhibits gonadotropin secretion, follicle maturation, and ovulation. Â Also produces endometrial thinning.
I know this is a lot of jargon, but I also have the Taber's medical dicionary, and I love looking this up if you have more questions. Â This information came from Davis Drug Guide for Nurses, seventh addition, page 226.
 I think I'll throw in the Adverse reatctions and side effects as well. Pg 227:
CNS: depression, migraine headache.
EENT: contact lens intolerance, optic neuritis, retinal thrombosis.
CV:Â
CEREBRAL HEMORRHAGE, CEREBRAL THROMBOSIS, CORONARY THROMBOSIS, PULMONARY EMBOLISM, edema, hypertension, Raynaud's phenomenon, thromboembolic phenomena, thrombophlebitis.
GI: abdominal cramps, bloating, cholestatic jaundice, gallbladder disease, liver tumors, nausea, vomiting.
GU: amenorrhea, breakthrough bleeding, dysmenorrhea, spotting.
Derm: melasma, rash.
Endo: hyperglycemia.
Misc: weight change.
*CAPITALS indicate life-threatening