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Do Contraceptive Pills cause Abortion?

By Patrick McCrystal MPSNI / MPSI

In my experience as a pharmacist, many women are horrified when they realise they may be aborting their own child by using the pill or other products. "Why didn't anyone tell us?" they ask.

The abortion-causing nature of the pill was the clinching factor in 1993 in my ceasing to dispense contraceptive drugs as a pharmacist, even though it meant subsequent unemployment for three years in my profession.

How is the pill abortion-causing?

Monthly process
Each month, an ovum is released from the ovary into the fallopian tube, and slowly makes its way towards the uterus or womb of the woman. Should intercourse occur, sperm are released into the vagina. These pass up through the cervix, into the uterus, and on up into the fallopian tube, to meet an on-coming ovum travelling in the opposite direction.

The sperm are inherently programmed to seek entry into the ovum. Should one succeed in doing so, it causes a chemical reaction that prevents any further sperm entry. The genetic material within the sperm's head is released, fusing with that of the ovum. This is conception (fertilisation).

A new human life has been created. Its sex, genetic makeup and individuality are set in motion. (At this point, a hormone called Early Pregnancy Factor - verifying the existence of a new life - is released into the mother's bloodstream. This can be detected by scientists using a specific blood test).

This newly conceived life, or embryo, makes its way down into the uterus (womb) where it implants in the womb lining (endometrium). This implantation usually occurs 5-7 days following conception. The baby now begins its 9 month gestation period ending in birth.

Abortion causing effect
One of the ways by which the 'pill' works is by;

"...the rendering of the endometrium unreceptive to implantation"  (1)

Put simply this means a newly created embryo is not allowed to implant in its mother's womb. This action takes place after fertilisation (conception), ie after a new life has been created. Thus it can be termed abortifacient (2,3) or abortion-causing. Indeed, the medical literature suggests this abortion-causing mode of action does occur during 'pill' use (4,5,20). Every chemical contraceptive preparation involving pills, injections, implants and intrauterine devices have this mechanism present as an inherent part of their birth control action.

Only a zero 0% ovulation rate at all times could truly assure a non-abortifacient effect. However the table below reports a wide range of 'break-through' ovulation varying with the type of preparation used. This wide range of ovulation indicates the very real risk of subsequent abortion for any embryo conceived in such circumstances.

Contraceptive Data

Preparation Ovulation Rate % Breakthrough Pregnancy
Combined Pill Up to 5%  ref: 5,6,7,8,20 0.1 *** 
Progestogen-only Pill 1-60% depending on type used
- see ref: 9,10,11,22
Intra-uterine Device Up to 100% ref: 12,13,14 0.6
Norplant Implants  10-50% ref: 13,15 0.09
Depo-Provera Injection  1% ref: 16,17 0.3
Key *** Figures for 1st year of use, for perfect usage. See Ref.(16)

'Break-through' pregnancy is the occurrence of an unexpected pregnancy during contraceptive use. The very existence of 'break-through' pregnancy proves that human embryos can indeed be conceived during chemical contraceptive usage and proceed to recognizable pregnancy (7,16,17,18). Such breakthrough pregnancies appear to occur even during 'perfect' usage, i.e. even when women do not forget to take their next dose (16,18). Stress, disease, infection, irregular pill use, vomiting, diarrhoea, and use of several drugs all lower the contraceptive effectiveness rates during typical use.

How many embryos are lost by the abortifacient effect at the endometrial stage is hard to quantify. However, the very concept of 'break-through' pregnancy is a powerful indication that embryos are indeed conceived during pill and contraceptive use, and some are certainly lost at the endometrial stage. The substantive effect of the pill on the endometrium, and its abortion-causing consequences, is highlighted by various authors (4, 20, 21).

It has been calculated that a silent, chemical abortion occurs once in every 200 menstrual cycles for a woman continually on the combined pill (19). In light of the millions of women using these contraceptive methods, this implies millions of pill-induced abortions worldwide.


There is a high degree of certainty that tiny human embryos die during contraceptive drug use. What is important however is not the actual figures involved but the fact that it happens at all. This reality is concealed from women all over the world.

Pill information leaflets either exclude reference to this mechanism of action, or else it is couched in such complicated medical terminology that pill users untrained in such terminology fail to understand the implications.

Given the dignity and preciousness of all human life at all stages of existence, the abortifacient nature of the contraceptive drug poses serious ethical and moral problems for all doctors and pharmacists involved in their promotion (21).


  1. ABPI Data Sheet Compendium. Datapharm Publications Ltd. 1996-1997 (Femodene) p1007.
  2. Stedman's Medical Dictionary 26th ed. William and Wilkins, London 1995.
  3. Blakiston's Gould Medical Dictionary 4th ed. New York 1979.
  4. Somkuti, S.G., Fritz, M. et al. The effect of oral contraceptive pills on markers of endometrical receptivity. Fertility and Sterility, 65(3) Mar 1996, pp 484-488.
  5. Van der Vange, N. Ovarian activity during low dose oral contraceptives. Contemporary Obstetrics and Gynaecology. Editor: Chamberlain, G., Butterworths, London, 1988, pp319-326.
  6. Grimes, D., Godwin, A., et al. Ovulation and follicular development associated with three low dose oral contraceptives: A randomised controlled trial. Obstetrics and Gynaecology, 83, (1) 1994, pp29-34.
  7. Westcombe, R., Ellis, R. and Fotherby, K. Suppression of ovulation in women using a triphasic oral contraceptive. British Journal of Family Planning, 13, 1987, pp 127-132.
  8. Ehmann, R., Abortifacient contraception the pharmaceutical holocaust. Human Life International, Ontario, 1993, pp7-16.
  9. Langren, B.M. and Diczfalusy, E., Hormonal effects of the 300ug norethisteone (NET) minipill. Contraception, 21, 1980, pp87-99.
  10. Neal, M.J., Medical Pharmacology at a glance. Blackwell Scientific Publications, London, 1991, p67.
  11. Belfield, T., Contraceptive Handbook, 3rd ed. Family Planning Association, London, 1992, p37.
  12. Zatuchi, G. and Goldsmith, A., Long term Clinical experience with levo-norgestrel-releasing IUD. Intra-uterine Contraception. Harper and Row, Philadelphia, 1987, pp232-237.
  13. Croxatto, H.B., Diaz, S., et al. Plasma progesterone levels during long term treatment with levo-norgestrel and Copper IUD comparative trial. Contraception 49, 1994, pp56-72.
  14. Andersson et al, L-norgestrel and Copper IUD comparative trial. Contraception, 49, 1994, pp56-72.
  15. Shaoban, M.M. et al, Sonographic assessment of ovarian and endometrial changes during long-term Norplant use and their correlation with hormone levels. Fertility and Sterility, 59(5), 1993, pp998-1002.
  16. Hatcher, R.A., Trussell, J. et al., Contraceptive Technology 16th ed. Irvington Publishers, New York, 1994, pp637-687.
  17. Pardthaisong, T., Grey. R., In utero exposure to steroid contraceptives and outcome of pregnancy. American Journal of Epidemiology, 134,(8), 15 Oct 1991 pp795-803.
  18. Duncan, G., Harper, C. et al., Termination of pregnancy; lessons for prevention. British Journal of Family Planning, 15, 1990, pp 112-117.
  19. Kuhar, B.M. PhD, Abortifacient Drugs and Devices; Do the numbers add up?, published in Infant Homicides through Contraceptives, Eternal Life publishers, KY, USA, 1995, p26.
  20. Larimore, L., Stanford, J., Post-fertilisation effects of oral contraceptives and their relationship to informed consent. Archives of Family Medicine, 9 Feb 2000 pp126-133.
  21. Larimore, W., The abortifacient effect of the Birth Control Pill and the principle of 'double-effect' Ethics and Medicine 16:1 2000, pp23-30.
  22. Cerazette Data Sheet 1% ovulation reported as of 13 Sept 2007.

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