The embryo has not even reached the uterus yet. Often times it does not successfully implant and if life actually begins at conception it logically follows that the woman's body has naturally murdered a person. But, no anti-abortionist would claim that because they know it would be outrageous. If everything goes right, it is not until two weels after conception that the pregnancy actually begins.
But, even at this early stage a lot of cases are miscarriages before the woman even knows she is pregnant. So, truth is that life does not begin at conception. Conception is simply the starting point of a very long process that only if completely uninterrupted for more than nine months will result in the birth of a human person (and even then stillbirth can happen).
Life does not begin at conception. That is not science and we do not write laws or strip away rights based on potential in any other context.