Patient's question:
On April 7, 2003, an ultrasound was performed, and the report indicated that the fetus was 66 days old. Please clarify whether these 66 days are calculated from the actual day of conception or the first day of the last menstrual period. What are the respective dates for the actual day of conception and the first day of the last menstrual period? Are they February 14th and February 1st or January 31st, respectively? Thank you.Doctor's answer:
First, you should understand that the pregnancy duration calculated by ultrasound is also an estimated value. It is calculated based on the size of the gestational sac measured. There can be discrepancies in the calculated pregnancy duration if there are variations in the measured values.The pregnancy duration calculated by ultrasound is based on the first day of the last menstrual period. In medicine, pregnancy duration is typically calculated from the first day of the last menstrual period. The due date is also determined from this day, and 280 days of pregnancy corresponds to the gestational period. It is not necessary to calculate the specific time of intercourse or conception.