How we research and correct content
Pregnancy information affects real decisions. This is how we choose sources, write, check and fix what we publish.
Sources last checked . How we write and check
Source hierarchy
- Clinical guidance from professional bodies: ACOG, AIUM and SMFM for US dating and care; NICE and the NHS for UK pathways, labeled as UK-specific.
- Public-health agencies: CDC, the NHS and MedlinePlus (US National Library of Medicine).
- Peer-reviewed research for numbers, such as how often babies arrive on the due date, cited with the study population and its limits.
- Hospital patient education from major academic centers, such as Cleveland Clinic, for plain-language descriptions of development.
We don’t cite forums, other pregnancy apps or commercial pregnancy sites as evidence. Citing a source doesn’t mean it endorses us.
How content is written
Every medical statement on the site carries a numbered citation next to it, linked to a source list at the bottom of the page. Statements must be supported by the source they cite. When sources disagree, for example on which week the second trimester starts, we say so and explain which convention we use and why.
Content is researched and drafted with the help of AI tools, then checked statement by statement against the cited sources before publishing. Formulas are implemented in code and verified by automated tests against worked examples from the sources; see our methodology.
Review status
Variable Ratio publishes this site. We are not a medical practice and the site has not yet been reviewed by a clinician. We don’t describe content as “medically reviewed” and we won’t until a named, qualified clinician has reviewed it. When that happens, the reviewer’s name, qualifications and review date will appear on the pages they reviewed.
Each page shows the date its sources were last checked. We change that date only when we actually re-check the page.
When we update content
- When an issuing body revises guidance we cite, such as an ACOG committee opinion or a NICE guideline.
- When a reader reports an error and we confirm it.
- On a scheduled review of every page at least once a year.
Corrections
Email hello@pregnancyduedatecalculator.com with the page address, what is wrong, and a source if you have one. We aim to acknowledge reports within a few working days. If we confirm a material error, we fix it on every affected page, including calculations, and note significant changes in the methodology change log.
Independence
The site currently has no advertising, sponsorship or affiliate links. If that changes, ads and affiliate links will be clearly labeled where they appear, will never be targeted using pregnancy dates, and will not influence what we write. An optional newsletter, if we ever offer one, will never be required to see results.