Due Date & Gestational Age
Estimate due date and gestational age using last period and regular cycle length.
Pre-filled values are examples, not personal facts or current local rates. Replace them before calculating.
Calculation method and references
EDD = LMP + 280 days + (cycle ? 28). Estimated gestation uses the adjusted anchor; ultrasound dating takes precedence.
NHS: due date and clinical dating
Method reviewed: 2026-09-08
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{"fields":[{"key":"lastPeriod","label":["末次月經(jīng)第一天","First day of last period"],"type":"date","value":"2026-07-01"},{"key":"cycle","label":["規(guī)律周期長(zhǎng)度（天）","Regular cycle length (days)"],"type":"number","value":28,"min":21,"max":35,"step":1},{"key":"asOf","label":["查詢(xún)?nèi)掌?quot;,"As-of date"],"type":"date","value":"2026-09-08"},{"key":"regular","label":["日期可靠且周期規(guī)律（非輔助生殖）","Reliable date and regular cycles; not IVF"],"type":"select","options":[["yes",["是","Yes"]],["no",["否","No"]]],"value":"yes"}],"title":["預(yù)產(chǎn)期與孕周估算","Due Date & Gestational Age"],"engine":"pregnancy-dates","scope":["日期不確定、周期不規(guī)律或輔助生殖請(qǐng)采用產(chǎn)科給定日期。僅估算，不判斷懷孕、胎兒健康或選擇分娩時(shí)機(jī)。","Uncertain dates, irregular cycles and assisted reproduction need clinical dating. Not a pregnancy test or assessment of fetal health."]}