Can some forms of birth control cause abortions?

If you believe that life begins at conception and that abortion is murder, then please read this!

Many women today choose the convenience of chemical birth controls - either birth control pills, shots, or IUD's. But how do they work? The best way to find out is to read the Full Prescribing Information provided by the manufacturer. These can be obtained by looking on-line, checking Physicians' Desk Reference, or by asking your pharmacist. Once you have this, look under the heading "Clinical Pharmacology". This is where the manufacturer tells how the birth control works. Most chemical birth control methods have three mechanisms. Although the primary mechanism is inhibition of ovulation, other alterations include changes in the cervical mucus, which increase the difficulty of sperm entry into the uterus, and changes in the endometrium which reduce the likelihood of implantation.[1]It's that last phrase which should concern Christians. This means that a fertilized egg would be unlikely to be able to implant in the uterus. If life begins at conception, then this is an abortion.
[1]Physicians' Desk Reference (Montvale, NJ: Medical Economics, 1998)