- Implantation — it is a change in location of the human embryo from the fallopian tube to the uterus. Again, when sperm and egg unite, a unique human life has begun. And this, fertilization/conception, occurs before implantation.
 
- Heartbeat or brainwaves — those are just developmental breakthroughs.
 - Pain sensation —it is a stage in development ( Congenital Insensitivity to Pain (CIP) is a rare genetic condition where individuals cannot perceive pain from birth, so this stage never develops in some people. Are they less human because of this lack of sensation?)
 
Image: Michigan Advance

A baby at 7-8 weeks. Image from 'LiveAction'