Why are ultrasounds so confusing? I don't understand them at all.?

Question

Everytime they tell me how far along i am i count back and it lands me at may 17. the day my period ended. how in the world could i have conceived so early? But then i found out its fetal or gestational age. and they added on 2 weeks. so if i count back 2 weeks from may 17 why did my period come on? or do i count forward to may 31? so what is may 17 then? is that the day i ovulated?

Answer 1

Do not use ultrasounds for dating as they will give you many false answers. Take the first day of your last period and count forward 42 weeks if you are a first-time mother. Don't let anyone change this date with ultrasounds or measuring. Best wishes, G

Answer 2

Ultrasounds are estimates only. They are not exact. As long as your scan dates you within a week or so of your due date based on your LMP, you use the due date based on your LMP and it doesn't change.

Don't try to over analyze things. Most women do not know when they ovulated or conceived, which is why they use the LMP date to calculate the due date.

Answer 3

Ultrasounds are estimates, and the further you are along, the less you can rely on them for exact dates,as every baby developes in a unique way.

They usually calculate from the first day of your last period + 40weeks onwards.

Or from the exact date of conception 38weeks onwards.

Ultrasounds are based on a 40week pregnancy, thus if they said May 17, you actually only conceived between the 25-31 of May, depending on your cycle

Hope this helps

Answer 4

Pregnancy is counted from the first day of your last period. You conceive about 2 weeks after the first day of your last period.( On average).    

Answer 5

The way pregnancy is calculated is from the first day of your last period. So when they say you are 4 weeks, you probably just had s*x and conceived about 2 weeks before and had your period 4 weeks before. That's just how it's calculated from the first day of last period.

Answer 6

They always take the date of conception as the last day of your last menstrual period. I don't know why, they just do! Assuming a regular 28 day cycle, you would have ovulated 2 weeks after that, so around May 31. By the time your baby is actually conceived, you are classed as being 2 weeks pregnant! It's always seemed really strange to me, that I could be classed as being pregnant before my egg was even released!

As I say, I have no idea why they add that time on, someone who knows more than me might be able to tell you why. HTH, even a little.