Data API and MCP server

BabyData exposes its baby-and-pregnancy calculators as a free, read-only JSON API and a Model Context Protocol (MCP) server, so an AI agent gets the same numbers from the same rules as the on-page tools. The endpoints cover due date, ovulation, pregnancy weeks and UK statutory maternity pay. Every response returns the rule it used and a primary UK source. No authentication, no PII, licensed CC BY 4.0. Pregnancy outputs are informational only, not medical advice, and are reviewed by our editorial team against NHS and gov.uk guidance.

Informational only, not medical or financial advice. These tools return estimates, not diagnoses or guarantees. Confirm pregnancy questions with your midwife, GP or NHS 111, and statutory pay on gov.uk.

REST endpoints

All endpoints are GET, return JSON, and accept query parameters. Dates are YYYY-MM-DD.

MCP server

A Model Context Protocol server is available at /mcp (streamable-http, JSON-RPC 2.0, protocol version 2025-06-18). It exposes the same four calculators as MCP tools:

• calculate_due_date
• calculate_ovulation
• pregnancy_weeks
• maternity_pay

The MCP manifest is at /.well-known/mcp.json and the OpenAPI 3.1 description at /openapi.json.

Methods and sources

Each response carries the rule it applied. Due dates use Naegele's rule (LMP plus 280 days, conception plus 266, IVF transfer plus 266 minus embryo age), as the NHS dates pregnancy. Ovulation is cycle length minus 14, with the fertile window the 5 days before ovulation plus ovulation day. Statutory Maternity Pay follows the gov.uk rule: 6 weeks at 90% of average weekly earnings, then 33 weeks at the lower of the flat rate or 90%. The names and births data draws on the ONS Baby names in England and Wales dataset, ONS births, National Records of Scotland and NISRA.

Terms

Read-only, no authentication, no personal data is stored. Licensed under CC BY 4.0: reuse the figures with attribution to BabyData. The statutory maternity pay flat rate is a placeholder until confirmed on gov.uk at launch.