As you prepare yourself to explain reasons for the pro-life position, Scott Klusendorf has developed a simple explanation of why a baby in the womb shouldn’t be considered to be any different than one just born.  He presented his outline based on the acrostic SLED on Focus on the Family. His ideas are also explained in his SLED article.  His four points touch on the differences in size, level of development, environment and degree of dependence of the pre-born baby vs other humans.

• (S)ize: Embryos are smaller than newborns, but toddlers are smaller than adults and women are generally smaller than men.  There’s no reason larger people should have more rights than a smaller ones
• (L)evel of Development: This idea is similar to size in that a 14 year old in mental development or self-awareness isn’t more of a person than a 4 year old, nor a 4 year old more of one than a baby of 4 weeks of gestation.  People with reduced mental functions such as those with Alzheimer’s or someone sleeping do not lose their humanness because of their impaired capacity
• (E)nvironment: A change of location of a few inches from inside the mother to outside to womb does not alter the nature of the baby from a non-person to a person
• (D)egree of dependency: If complete independence is a criteria for humanness, than people dependent on insulin or those on dialysis would be not be human.  Newborns would be in a similar position given that they’re completely dependent on their parents to care for them.