When Does the Starting Point of Pregnancy Begin?
Many pregnant women are eager to know their expected date of delivery after finding out they are pregnant. However, to accurately calculate the expected date of delivery, it starts from the beginning of pregnancy, which many people do not understand and hence might make a mistake. For women with regular menstrual cycles, with intervals of around 28 days, the calculation usually starts from the first day of the last menstrual period. If calculated from the date of conception, the gestational age will be approximately two weeks shorter than what we typically calculate. The starting point of pregnancy is not always easy to determine as it is based on the woman's menstrual cycle and ovulation period. For women with regular menstrual cycles and ovulation periods, the pregnancy is typically calculated from the first day of the last menstrual period.
How to Calculate Pregnancy Weeks?
1. Based on the Last Menstrual Period:
Add 9 or 3 to the month of the last menstrual period's ending date to get the expected month of delivery. Add 7 days to get the expected date of delivery.
2. Based on the Date of Fetal Movement:
If you cannot remember the date of your last menstrual period, you can estimate it based on the date of fetal movement, which typically starts around the 18th to 20th week of pregnancy. The estimated formula is: add 20 weeks to the date of fetal movement for primiparous women and 22 weeks for multiparous women.
3. Based on Ultrasound Examination:
During an ultrasound examination, doctors can measure the biparietal diameter of the fetal head, the crown-rump length, and the length of the femur to estimate the gestational age and thus predict the expected date of delivery (this method is mainly used for diagnostic purposes in ultrasound examinations).
