Week by week

Pregnancy and baby's growth

It's exciting to see how a baby develops over the course of a pregnancy. Changes happen rapidly, which is why it's interesting to know what happens to your baby's growth and to your body week by week. The length of a pregnancy is in trimesters; a trimester is a three-month period. Within each trimester, people will refer to the number of weeks.

The first two weeks involve the initial conception when your egg is fertilized by the father's sperm. Our week-by-week look at pregnancy begins with week 3, when the fertilized egg is attached to the wall of the uterus and begins to grow.

In this section:

1st trimester
2nd trimester
3rd trimester