Pregnancy Timeline: How is Gestation Age Determined?

Question
I just found out that I'm pregnant. But, I don't remember my last menstrual cycle. How could the doctor tell how many weeks am I. Do they do a sonogram or something? An can they tell when I got pregnant or when I was fertilize.

Answer
Hi Unique,

Congratulations!

Yes the doctor will have an ultrasound done and this will tell you how far along and developed the fetus is. Based on these measurements from the ultrasound, they will be able to determine about when your last period was.

It would be impossible to pinpoint the exact day or minute you conceived, but based on when your period was, you can count forward and determine this. the FIRST day of your last period would be day ONE. (Yes, the period is considered part of the pregnancy cycle) Then count forward 10-14 days, and this time is when you most likely conceived.

I hope this helps!
Good luck!
andi