Usually, a pregnancy is 40 weeks in length, counting from the first day of your last menstrual cycle period.
Pregnancy is broken down into three phases, which are called trimesters.
The first trimester lasts 12 weeks, the second from 13 to 27 weeks and the third from 28 to 40 weeks. Routine tests are offered to all women after their pregnancy has been confirmed by their doctor. You are also offered a urine test to see if you have a kidney infection. Other special tests are available to women who may be at risk for an abnormal pregnancy. See your doctor as soon as you know or suspect you are pregnant.