My doctor wants to do a biopsy for uterine cancer due to some recent physical problems and family history of uterine cancer. However, my doctor wants to be sure I am not pregnant before doing the biopsy, since I very recently had unprotected sex with my husband. He has recommended two pills, called "Plan B." I took the first pill and was supposed to take the second one at 3:00 a.m. this morning but for some reason was uneasy about it. What should I do since I've now taken the first pill? (My doctor told me it wasn't like the abortion pill.)
Plan B is levonorgestrel (.75mg given as two doses, 12 hours apart, administered within 72 hrs of intercourse) to stop a conception from occurring or advancing. It may suppress ovulation, alter tubal transport, or alter the lining of the endometrium, possibly preventing implantation. If you avoid taking the 2nd pill you will lessen the probability of any or all of the above (potential) effects from occurring. So if you want to lessen the risk of a post-ovulation effect, you should NOT take the second pill. If you are already past the 72 hour mark, anything you do now will not likely matter much.
To document that you are or are not pregnant you can ask for a quantitative HCG (blood test). It may be positive a few days before the anticipated (missed?) menstrual period. Or you can have an ultrasound of your womb (which may also help in identifying any intrauterine abnormality/growth such as a polyp or a cancer even without a biopsy).
For more information on the birth control pill, see Randy Alcorn’s book Does the Birth Control Pill Cause Abortions?