However, as pregnancy progresses, the rates of fetal growth begin to vary from pregnancy to pregnancy.This is why ultrasound measurements can’t be used to accurately predict the age of the baby in the later stages of pregnancy.
The first step is locating the date of your LMP on the wheel.
When you line up that date with the indicator, the wheel displays your due date.
A repeat ultrasound provides valuable information about the growth of the fetus and may reassure you and your doctor that the change in due date is reasonable. Ultrasound measurements for estimating the age of a fetus are more accurate during the early stages of pregnancy.
In the first few weeks, fetuses tend to develop at the same rate.
Learn more about how your body changes during your pregnancy.
Calculating due date is a fun thing to do both when you are pregnant and trying to conceive (or even just secretly dreaming about it).
Your doctor may change your due date if your fetus is significantly smaller or larger than the average fetus at your particular stage of pregnancy.
Generally, your doctor orders an ultrasound to determine the gestational age of your baby when there’s a history of irregular periods, when the date of your LMP is uncertain, or when conception occurred despite oral contraceptive use.
Your doctor may change your due date based on the ultrasound measurement.