速答：常见预产期推算

基于 Naegele 公式：末次月经 (LMP) 第一天 + 280 天（40 周）。日期速算：年 + 1，月 − 3，日 + 7。下方为常见情况的速查表：

末次月经 (LMP)推算预产期 (EDD)距今天数 (假设今日 = 2026-10-02)
2025 年 12 月 20 日2026 年 9 月 27 日已过预产期 5 天
2026 年 1 月 1 日2026 年 10 月 8 日6 天后
2026 年 1 月 15 日2026 年 10 月 22 日20 天后
2026 年 4 月 15 日2027 年 1 月 22 日约 112 天后
2026 年 7 月 10 日2027 年 4 月 17 日约 197 天后
2026 年 9 月 1 日2027 年 6 月 8 日约 250 天后

参考：美国妇产科医师学会 (ACOG) Committee Opinion No. 700。仅约 5% 的宝宝在 EDD 当天出生，约 80% 在 ±2 周内出生。

预产期计算器

Use this free pregnancy due date calculator to estimate your due date and current week of pregnancy.
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输入末次月经日期

计算预估预产期和孕期里程碑

预产期是如何估算的

This calculator uses Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period, adjusted for your cycle length. This is the most widely used method for estimating due dates.

Note: Only about 4% of babies are born on their exact due date. Most arrive between 37-42 weeks. Your healthcare provider may adjust the due date based on ultrasound measurements.

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How our pregnancy due date calculator works

1

Enter your last menstrual period

Type the first day of your last period. This is the standard reference date used by most obstetricians.

2

We add 280 days

Naegele's rule: due date = LMP + 280 days (40 weeks). The calculator also shows the date range (38-42 weeks is full term).

3

See week-by-week milestones

Get your current week, trimester, and key dates: first prenatal visit, anatomy scan, viability (24w), and full term (37w).

Key things to know about our pregnancy due date calculator:

  • Due date accuracy: Only 5% of babies arrive on their exact due date. Most come within 2 weeks before or after. Treat the due date as a range, not a deadline.
  • Conception date: If you know your conception date (e.g. from IVF or tracking), add 266 days for an alternate due date. Conception typically occurs 14 days after LMP.
  • First vs subsequent pregnancies: First pregnancies average 40 weeks + 1 day. Subsequent pregnancies average 40 weeks + 0 days, but individual variation is large.

For related calculations, try our pregnancy calculator.

预产期推算（Naegele 公式）

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预产期计算器 - 末次月经/排卵日/试管期 推算 | CalcCentral