Fertilization

Fertilization (English spelling: fertilisation) is what happens when a female's ovum (or "egg") joins together with a male's sperm and they form a zygote. Fertilization is also called conception.

In humans, biologists call a fertilized egg a zygote. It is called an embryo from 3–8 weeks (the embryonic period.) Then after 8 weeks, it is called a fetus.

If it continues to grow normally it can eventually become a baby.

People have different beliefs about when life starts:

• Some people believe that life begins at conception.
• Some people believe that life begins after the embryonic period (when the organs form.)
• Some people believe that life begins when the fetus is able to live outside of the woman.
• Some people believe that life begins after a baby is born.

This difference in what people believe has led to many arguments over abortion.