One of my clients who is “past due” found this nice article that helped ease her mind. Janelle Durham, for Certification with Birth Education NW. Calculating a due date is a very challenging task as many factors go into the equation. This paper will examine the methods used by obstetricians to predict the date on which a baby will be born, and also examine how that forecasted due date affects the course of obstetric treatment.The purpose of the dating scan is to: Some abnormalities may also be detected at this scan, such as neural tube defects (spina bifida is a type of neural tube defect).This depends on whether you have agreed to have the screening and when the scan takes place.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.
You can ask your midwife or doctor before the scan if this is the case. Find out more about what happens during a pregnancy ultrasound scan.
The scan will usually show that your pregnancy is less far along than suggested by your LMP.
This means that accurate dating reduces your chance of having your labour induced because your baby is thought to be overdue.
At this time, the fetus is a little larger and easier to measure.
Even dating scans can be inaccurate for the due date, but they are never as inaccurate as using the menstrual period.