Your obstetrician is able to confirm and date your pregnancy with the use of an ultrasound scan. Your obstetrician will take various measurements of the gestational sac in early pregnancy, and later of the fetus. Your first scan will typically take place between 11 and 13 weeks into your pregnancy. Your dating scan will also allow your doctor to check that your baby is developing properly.
Your dating scan will typically take no more than half an hour, and you will be asked to arrive with a full bladder. Gel will placed on your stomach, and a hand-held scanning device will be moved over your skin, so that an image can be displayed on a screen. For more information on ultrasound scanning during pregnancy, click here.
As well as ultrasound scanning, your obstetrician will also take into account your last menstrual period to calculate your due date. Generally, the duration of a pregnancy is forty weeks from the first day of your last menstrual period.
Your obstetrician will also conduct a physical exam to support the date revealed by your ultrasound scan. This will include a pelvic exam, as the uterus moves according to the stage of pregnancy.