How accurate is 12 week dating scan
Having an ultrasound in the first trimester of pregnancy can be a thrilling experience. Bear in mind that you may need a second ultrasound before you know for certain if all is well.
It's wonderful to see a little blob with a heartbeat that will become your baby. If you are unsure of the first day of your last period you will be offered a dating ultrasound when you are between 10 and 14 weeks pregnant.
“Exercise extreme caution with regard to last menstrual period (LMP) on history taking.
Up to 50% of women are uncertain of their dates, or have an irregular cycle, or have just stopped the oral contraceptive pill (OCP), or are lactating or did not have a normal last period.
You would need a formal ultrasound performed by a qualified ultrasonographer (technologist) and reported on by a qualified sonologist (specialist doctor) to provide more detailed information and/or definitely confirm any possible findings by your maternity caregiver.
If you do know the conception date, this is classed as day 14 and not day one.But ultrasounds can also lift the lid on a few worries you might be having. The main reason for the ultrasound is to work out how many weeks pregnant you are, and to estimate your due date.The length of your pregnancy is calculated from the first day of your last menstrual period (LMP), even though you don't actually conceive until 14 days after your LMP, and later than this if your cycle is longer than 28 days.For example, it is very easy to determine the position of an unborn baby, but it requires a very experienced ultrasonographer to detect pregnancy problems or physical abnormalities in the baby.Even then, detecting some abnormalities is not always possible and in up to 10% of cases, a baby will be mistakenly thought to have an abnormality, but in fact be well and healthy.