It is really important to try and nail down your date of conception or “due date” as accurately as possible in the beginning of your pregnancy. This isn’t always easy to do, especially if your pregnancy was a surprise. The estimate of your baby’s age has a big impact on your prenatal care and your care provider’s recommends as you get closer to your due date. A big measurement of your baby’s health during your pregnancy is based on estimates of their size relative to your due date. Measuring the size of your baby in the womb is not an exact science. Unfortunately we have no way to measure weight or height with 100% accuracy before a baby is born. The most accurate methods we have usually combine an ultrasound with some calculations to come up with the size of your baby. This episode answers a questions about the accuracy of ultrasound measurements.