Here is a most compelling interview in which writer Sue Ellin Browder asks Maureen Condic, associate professor of neurobiology and anatomy at the University of Utah School of Medicine and a senior fellow at The Westchester Institute for Ethics & the Human Person, about the cold, hard facts revealed by the ever-advancing science of embryology.
I recommend you not only read it but probably print it off and save it for future reference. After all, there's nothing better to "spice up" your letters to editors, politicians, etc. than some indisputable science.
(Hat tip: Hyscience)