The calculation of the number of weeks of pregnancy is based on the start of the last menstrual period.The following steps explain this in more detail.
- Check the start date of the last menstrual period: this is the starting date for the number of weeks of pregnancy.
- Calculation of expected delivery date: The expected delivery date is 280 days (40 weeks) after the start of the last menstrual period. This is considered the standard gestational period.
- Calculate the current number of weeks of pregnancy: the difference between today’s date and the start of the last menstrual period is converted into weeks.
- Ultrasound correction: an ultrasound scan in early pregnancy may correct the number of weeks of gestation based on actual foetal growth. This is done if the last menstrual period start date is not accurate or if the date of ovulation differs from the normal date.
例
- If the last menstrual period started on 1 January 2023, the expected delivery date would be 8 October 2023 (280 days later), which would be 31 weeks as of 1 August 2023.
Points of Attention:
- The number of weeks of pregnancy is very important to monitor the health of the mother and the foetus. For this reason, regular visits to the doctor are recommended.
Using this method, you can easily calculate your gestational week and expected delivery date, but the exact number of weeks is best confirmed by a doctor.
Supervisor of the article
Dr. Hiroshi Oka
Graduated from Keio University, Faculty of Medicine
Doctor of Medicine
Medical Doctor
