When you go for an ultrasound and they tell you e.g. 18 weeks and 1 day... do you count back from that day 18 weeks and one day?

Is the date given here your conception date or do you have to take off two weeks
I am getting confused with all this

Quote:

---

Originally Posted by jesswright07

when you go for an ultrasound and they tell you e.g. 18 weeks and 1 day... do you count back from that day 18 weeks and one day?

is the date given here your conception date or do you have to take off two weeks
i am getting confused with all this

---

The date obtained by ultrasound is the gestational age of the fetus (baby). It is one of the most accurate non-invasive means to estimate the gestational age, especially when performed between 7-12 weeks of age.

The gestational age is typically estimated from the first day of a woman's last menstrual period and is typically 14 days or 2 weeks greater than the fertilizational or conceptional age. In other words, the fetus is actually about 2 weeks younger than the date you get via ultrasound, or that you estimate when you calculate based on your last menstrual period (LMP).

The conceptional age/time can be recorded down to the hour/minute in fetuses conceived by in-vitro fertilization, but as you can image this is much harder in parents who don't conceive this way.. so it has to be estimated, and it could get messy guessing the wrong time.. and so it is estimated to be 2 weeks after a woman's LMP based on the ovulatory cycle.

Conception date/age = Gestational age - 2 weeks.

Hope this helps.