When does human life begin?

Conception

When does human life begin?

We know that a woman's pregnancy results from a combination of several biological processes. Among these are:

 
- The union of a male and female sex cell which produces a new single cell called zygote.
   This process is called
fertilization.
 
- The growth of the zygote by cell division, resulting in a hollow ball of cells called
   blastocyst. This process is called
segmentation.
 
- The attachment of the blastocyst to the lining of the uterus. This process is called
  
implantation.
 

If anything goes wrong with even one of these processes, no pregnancy can occur.
Still, for certain scientific reasons many developmental biologists prefer to speak of a conception as soon as the process of fertilization is completed. On the other hand, some reproductive physiologists believe for their own scientific reasons that a new life begins with the process of implantation. For them, no conception occurs unless the fertilization leads to pregnancy.

[Course 2] [Description] [How to use it] [Introduction] [Conception] [Historical Notes] [Beginning of Life?] [No definite answer] [Egg and Sperm] [Coitus] [Fertilization] [Segmentation] [Implantation] [Multiple Pregnancies] [Pregnancy] [Birth] [Infertility] [Contraception] [Abortion] [Additional Reading] [Examination]