Birth control pills have got abortion potential. It can cause miscarriage in the early pregnancy. That is even before the embryo gets implanted. This is not because it has got adverse effect on the embryo. This is because it has affected the uterine lining where the baby goes and implants. So because of that early miscarriages can happen. Also whenever a baby gets pregnant with birth control pills we should be cautious about ectopic pregnancy because of changes which take place in the fallopian tubes. But when the pregnancy successfully happens it goes to the extent of four months of pregnancy, abortion cannot happen because the birth control pills do not have any adverse effect on the foetal development.
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