Accuracy ultrasound dating conception
Ultrasound can be used in conjunction with estimates based on last menstrual period to determine a more accurate gestational age.
When people discuss how far along in pregnancy someone is, they tend to do so in general terms: “She’s in the first trimester” or “She’s four months along.” However, many people have only a vague idea of what those phrases really mean.
Instead, we most commonly date pregnancies from the first day of the last menstrual period (LMP).
One reason for not dating pregnancies from the day of conception is that we cannot know that day exactly (excluding cases of assisted reproduction), but we can know the first day of LMP, based on what a patient reports to us.
However, the timing of the actual delivery is not so predictable.
Some women will deliver on their due date, others before, and others after.
Sometimes we do use a trimester system if we are seeking to describe how far along a woman is in general terms.
Unsure of when you conceived and how far along your are?
An ultrasound is the most accurate way to see how far along your pregnancy is.
Estimating conception date can also be more difficult for women who have irregular periods, or for those who don't remember the first day of their last period.
In cases like these, one of the more accurate ways to estimate gestational age is through the use of an ultrasound.