妊娠予定日計算機
最終月経日（LMP）に基づいて予定日を推定します。ネーゲレの法則（LMP + 280日）を使用します。
推定出産予定日
週
現在の週数
w d
残り日数
妊娠期
推定受胎日
この計算機はネーゲレの法則（LMP + 280日）を使用しています。実際の予定日は異なる場合があります。正確な推定については医療専門家にご相談ください。
Frequently Asked Questions
How is a pregnancy due date calculated?
The due date is calculated by adding 280 days (40 weeks) to the first day of the last menstrual period (LMP). This is known as Naegele's rule. Only about 5% of babies are born exactly on their due date; most arrive within two weeks before or after.
What are the three trimesters of pregnancy?
The first trimester spans weeks 1–12, the second trimester covers weeks 13–26, and the third trimester is weeks 27–40. Each trimester has distinct developmental milestones and different prenatal care recommendations.
How accurate is a due date calculator?
A due date based on LMP is an estimate. Only 4–5% of babies arrive on the exact due date. An ultrasound in the first trimester can provide a more accurate estimate, typically within 5–7 days. About 80% of babies are born between weeks 38 and 42.