Our sources and how we check facts
Health information must be right. This page explains where our facts come from, how we check them, and what we do not do.
Where our facts come from
We use only official and professional sources:
- ACOG, the American College of Obstetricians and Gynecologists
- NHS, the UK National Health Service
- RCOG, the Royal College of Obstetricians and Gynaecologists
- WHO, the World Health Organization
- CDC, the US Centers for Disease Control and Prevention
- National health ministries and official government sites, for local rules such as parental leave and care schedules
The exact formulas and every source we use for dates are on how we calculate.
How we check
- Every fact is linked to its source, with the date we checked it.
- Every formula is tested by computer against worked examples, thousands of random dates, leap years and time zones.
- Urgent warning signs come only from official lists, with a link to the list.
- We re-check sources at least once a year, and right away when guidance changes.
Our content is written from official sources (ACOG, NHS, WHO). It is not reviewed by a doctor. We never write “medically reviewed”.
Estimates, not medical advice
Our tools give estimates. They do not diagnose anything and do not replace your doctor or midwife. Always follow the dates and advice of your care team. If something feels wrong, see urgent warning signs.
Last updated: October 25, 2026