Pregnancy conception dating
It shouldn't be uncomfortable, and you don't need a full bladder Your sonographer will give you a report of the scan, which will tell you exactly how many weeks pregnant you are.
Therefore, from 13 weeks, or if your baby is longer than 84mm, the circumference of the head becomes the best way to measure your baby. Evaluation of gestation emedicine.[Accessed July 2017] Newson L.
If you do know the conception date, this is counted as day 14, not day one.
If your cycle is irregular or you've recently been on the pill, working out the date from your LMP probably won't work. If the scan date differs from your period dates, the scan date will be used.
However, conception doesn't actually occur until around 14 days after your LMP, or later if your cycle is longer than 28 days. Multiple pregnancy: antenatal care for twin and triplet pregnancies CG129.
You may know when your LMP was, but not when you actually conceived.As long as the timings are right, you can have the NT scan and blood test at the same appointment as your dating scan. That's because the screening test needs an accurate due date to be reliable.