预产期计算器
根据末次月经日期（LMP）估算预产期。使用Naegele法则：LMP + 280天。
预估分娩日期
周
当前周数
w d
剩余天数
妊娠期
预估受孕日
此计算器使用Naegele法则（LMP + 280天），实际分娩日期可能有所不同。请咨询医疗专业人员以获取准确估算。
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.