1st trimester scans will be done to:
- Confirm a normal intrauterine pregnancy
- Exclude extra-uterine pregnancy or miscarriage
- Determine the fetal age by measuring the length of the embryo (this will establish the dating of the pregnancy)
- Determine the baby’s heart rate
- Look for multiple pregnancies (twins, triplets, etc.)
- Identify problems of the placenta, uterus, cervix, and ovaries
How accurate is pregnancy dating?
A measurement of the length of the embryo at 7-11 weeks’ gestation is accurate to within about 3 days. Beyond this time the accuracy reduces due to flexion (bending) of the fetus and individual’s growth variance.