{"uid":"cap_sDHNZRo0Zh6NuD66dN9ki","slug":"pregnancy-due-date-calculator-naegele-rule-546a42ad","name":"Pregnancy Due Date Calculator (Naegele Rule)","description":"Estimated due date, gestational age and trimester from the last period (Naegele rule), with key milestone dates.","url":"https://fitness-calc.x402tookit.com/due-date?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["lmp"],"properties":{"lmp":{"type":"string","description":"First day of last menstrual period, YYYY-MM-DD"},"asOf":{"type":"string","description":"Date to compute the current gestational age for (default today)"},"cycleDays":{"type":"integer","description":"Average cycle length, 21 to 45 (default 28)"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"lmp":{"type":["null","string"]},"asOf":{"type":["null","string"]},"source":{"type":["null","string"]},"dueDate":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"cycleDays":{"type":["null","number"]},"trimester":{"type":["null","string"]},"disclaimer":{"type":["null","string"]},"milestones":{"type":["null","object"],"properties":{"fullTermEnds":{"type":["null","string"]},"fullTermStarts":{"type":["null","string"]},"endFirstTrimester":{"type":["null","string"]},"conceptionEstimate":{"type":["null","string"]},"endSecondTrimester":{"type":["null","string"]},"anatomyScanWindowEnd":{"type":["null","string"]},"anatomyScanWindowStart":{"type":["null","string"]}}},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"gestationalAge":{"type":["null","string"]},"computedForDate":{"type":["null","string"]},"gestationalDays":{"type":["null","number"]}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Jmu0j4PUfmZ7rZCWZFVMp","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Calculates estimated due date, gestational age, trimester, and key pregnancy milestones from the last menstrual period date using the Naegele rule.","exampleAgentPrompt":"My last period started on March 15, 2025 and my average cycle is 30 days — can you calculate my estimated due date, what trimester I'm in as of today, and all the key pregnancy milestones?","exampleUseCases":[{"title":"First-time mother checking due date","prompt":"My last menstrual period started on January 8, 2025 and my cycle is usually 28 days — what's my estimated due date and when does each trimester end?"},{"title":"Tracking gestational age mid-pregnancy","prompt":"My LMP was November 20, 2024 with a 32-day cycle. As of today, how many weeks and days pregnant am I and what trimester am I in?"},{"title":"Planning anatomy scan appointment","prompt":"Last period was February 3, 2025 with a normal 28-day cycle — when is my anatomy scan window and what other milestone dates should I know about?"}],"resultDescription":"Returns the estimated due date (YYYY-MM-DD), current gestational age as a human-readable string and in days, the current trimester, a summary, and a milestones object with dates for conception estimate, end of first trimester, end of second trimester, anatomy scan window start/end, full term start, and full term end. Also includes the LMP and cycle length used, the asOf date computed for, and a medical disclaimer.","failureModes":["Missing required 'lmp' parameter returns an error","Invalid date format for lmp or asOf causes a parse error","Cycle length outside 21–45 day range may be rejected or clamped","Future LMP date may return unexpected or degraded results","Network timeout or upstream service unavailability"],"whenToPreferThis":"Use this endpoint when you need a quick, structured computation of pregnancy due date and milestones from a last menstrual period date, especially when you need trimester classification and key milestone dates (anatomy scan, full term) in a single call. It applies the standard Naegele rule and supports custom cycle lengths, making it more precise than a generic 280-day fixed calculation.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:13:44.357Z","isFirstParty":false,"canonicalSlug":"pregnancy-due-date-calculator-naegele-rule-546a42ad"}