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Pregnancy Due Date Calculator (Naegele Rule)
x402
Pregnancy Due Date Calculator (Naegele Rule) is a paid API for AI agents from fitness-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Calculates estimated due date, gestational age, trimester, and key pregnancy milestones from the last menstrual period date using the Naegele rule.
Price / call$0.02
Success—
StatusUnknown
How this service works
Estimated due date, gestational age and trimester from the last period (Naegele rule), with key milestone dates.
Output
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.
Example use cases
First-time mother checking due date
“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?”
Tracking gestational age mid-pregnancy
“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?”
Planning anatomy scan appointment
“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?”
Technical details
Endpoint
GEThttps://fitness-calc.x402tookit.com/due-date?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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