Week 1
Trimester 1 of your pregnancy
First, a note about timing: Your pregnancy is dated from the first day of your last menstrual period. So, for the purposes of the calculations made by your health care professional, you are considered to have become pregnant about 2 weeks before you actually conceived.
During week 1, your normal menstrual period occurs. Your body sheds the lining of the uterus and prepares to make a new one that will host your baby.