Accurate Due Date Estimation with Ultrasound
When it comes to determining the due date of a pregnancy, the American College of Obstetricians and Gynecologists recommends relying on ultrasound measurements taken during the first trimester. This method is considered to be the most accurate. In cases where the last menstrual period (LMP) date is known and reliable, research indicates that the prediction for the date of birth is not significantly different.
Calculating Due Dates for Multiple Births
When it comes to multiple births, such as twins or triplets, the timing of delivery is often different from that of single births. In most cases, multiple births occur approximately two weeks earlier than single births. However, despite this difference, the method of calculating the due date remains the same as it would for a single birth.
Factors such as the last menstrual period (LMP), conception date, and day of fertilization do not affect the due date for multiple births. Instead, the due date for multiples is determined based on the same timeline as a single birth.
Typically, multiple births occur between 35 and 38 weeks of gestation. However, if a physician uses a sonogram to calculate the due date, they take into account the size of the larger twin to determine the estimated date of delivery, also known as the EDD.