以下のガイドはまだ日本語に翻訳されていないため、英語で表示しています。計算機自体はすべて日本語に対応しています。
この計算機の使い方
- Choose the date you know: first day of last period, conception date, or IVF transfer date.
- Enter the date (and cycle length if using your last period).
- The result shows your gestational age in weeks and days as of today. Change today's date to check a different day.
計算式
Gestational age is counted from the first day of the last menstrual period, so it includes about two weeks before conception. It is the standard way healthcare providers describe pregnancy progress.
Gestational age = today − (due date − 280 days)
Trimesters: 1st < 14 weeks, 2nd 14–27 weeks, 3rd ≥ 28 weeks
Example
- Last period started 70 days ago with a 28-day cycle.
- Gestational age = 70 days = 10 weeks 0 days, first trimester.
- 210 days remain until the due date.
よくある質問
Why am I 'pregnant' two weeks before conception?
Dating from the last period is a convention because that date is usually known, while the exact conception date usually isn't.
What is the difference between gestational and fetal age?
Fetal (embryonic) age counts from conception and is about two weeks less than gestational age.
Can my weeks change after an ultrasound?
Yes. If an early ultrasound differs significantly from your period-based date, your provider may update your due date.