怀孕

人的生命从什么时候开始？

我们知道妇女怀孕是由于几个生物过程导致的结果。这些生物过程是：

 
- 男女性细胞融合，由此产生一个被称为合子的单一新细胞。这一过程称为受精
 
- 通过细胞分裂，合子生长，产生由许多细胞构成的称为胚泡的有空腔球形体。这一过程称为卵裂。
 
- 胚泡附着到子宫内膜。这一过程称为植入。
 

如果伴随这些过程之一出了差错，怀孕就不可能发生。
尽管如此，出于科学研究原因，许多发育生物学家倾向于把授精过程一完成定义为怀孕。另一方面，一些生殖生理学家出于自己科学研究的原因，认为一个新生命体开始于植入过程完成之后。对于生殖生理学家来说，除非受精导致了妊娠，不然就无怀孕之说。

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.