The question of whether developing cells become sentient at the point an egg is fertilized or during the early embryonic stages is not known. It is known that each human being requires and leaves an ecological foot print on the planet (at minimum, this is the amount of the earth's acreage required to maintain a survival level for each person). At over 6 billion, there's already not enough acreage on the planet to meet the collective footprints of every person living (not to mention the resouces required by other species to survive). The UN estimates the worlds population will expand to between 7.9 and 10.9 billion by 2050.

Most Pro-Life anti-abortionists claim to own the moral high ground on abortion issues. They accuse women who have abortions (and those in the medical community who assist them) as propagators of genocide. In reality, genocide on a grand scale is being propagated by the exponentially increasing population (that continues to mushroom beyond the planet's resources capabilities). For every person born, there will be another person who will not have enough of the planet's resources to survive. This obviously doesn't take into account the distribution inequities that exist, but the ratio of the planet's resources to the cumulative needs of all the persons in existence has been quantified by a number of governmental and private organizations.

Our "enlightened" species has managed to over breed to lethal proportions (for ourselves and all the other species on the planet)! It is incomprehensible to me that the Pro-Lifers don't recognize that in trying to force their morals onto the reproductive functions of others, they are themselves furthering genocide. At the present rates of growth,
governments may eventually be forced to legislate the amount of reproduction any one person can have. Six billion people (and growing) are consuming  earth's finite resources at a break neck pace. This is mind boggling by any standard.

UN 1999 - Countries Legal Policies on Abortions

WWF - http://www.panda.org