How many weeks pregnant?

Yes they will always ask when's your last menstrual period is. If you have a very regular menses then it's easy to calculate but if you don't then it's difficult to know unless you do a scan which is more reliable. I have quite a regular menses and based on my last period, I was 11 weeks going to 12 weeks pregnant. But when I did my 1st ultrasound, I was only 10 weeks+ pregnant.