Silly Q about scan dates

[Sparks1007]

OK. First baby. Silly question. Just had a scan that my doc said showed pregnancy is at 5 weeks and to go back in a couple of weeks for a 7 week scan. When they say 5 weeks that means 5 weeks of developing pregnancy (since conception) rather than the 5 weeks from first day of lmp right There was a sac and a yolk on my scan. Am I interpreting correctly? Thanks!

No, they mean 5 weeks from LMP, or that the embryo's size is consistent with that gestation.

Yes, as PP said they mean five weeks from when they would expect your LMP to be.

Once you've had a scan you don't really have to think about LMP again as the scan dates are more reliable.

If you have longer or irregular cycles, then using LMP is usually not that helpful (for example, I have long cycles and when I conceived, LMP would have put me a week ahead of where I was - which was born out at the first scan).

At five weeks pregnant, you would have conceived ~ three weeks previously.

Hit post too soon, but the first two weeks of a dated pregnancy are the two weeks before conception occurred (ie. when the egg starts developing). So eight weeks pregnant is six weeks since sperm met egg, 12 weeks pregnant is 10 weeks since sperm met egg, etc.

5 weeks will mean 3 weeks since conception.

Just so you know I went for my first scan as an emergency scan which said 5 weeks (from first day of period) because I had a bleed. The next scan I went to would have been 8 weeks by that scans estimate but I was actually almost 10, which made more sense. She said measurements in early scans are a bit more of a guess

Thanks all. This is OP - just had to change my username. I thought it was 5 weeks from lmp then dates didn't seem to add up so then I thought it must be 5 weeks of development. What a palava. No foetal pole yet as it's early on. Hoping we'll be OK at the next scan.

Interesting to hear your experience @minilemonade. I didn't see my doctor as she's away so hoping when I see her for that second scan we'll all have a better idea of time along.

Thanks again all.