Early pregnancy dating ultrasound Ssexchat in usa
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.
Ultrasound scans are considered to be safe for you and your baby when performed by trained professionals.
However, sometimes, having a scan can cause unnecessary worry.
How big your baby will be depends on when you have the scan: After 13 weeks, your baby can curl up and stretch out, so measuring the length becomes less accurate.
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.
It may lead to you being given a high chance for Down's syndrome, when your baby is actually developing normally (false-positive result). Addition of non-invasive test to improve screening for pregnant women.
The dating scan will also show if you're expecting twins, triplets, or more.
It's helpful to know about twins early on, and it's easier to see whether or not they share a placenta during the first trimester.
For example, the NT scan for Down's syndrome has a false-positive rate of five per cent.
This means that, out of 20 women who have the scan, one woman will be wrongly told she has a high chance of having a baby with Down's syndrome.