How the evidence is linked
Each public note starts with a named source and citation, then becomes a claim and a timeline summary. A supporting page is added only when it has enough evidence to stand on its own. Public wording never adds more precision or certainty than the underlying claim.
Four ways timing is described
- By-age checkpoint: what a defined majority can do by an age. It is not a deadline.
- Broad achievement window: an observed lower-to-upper population span.
- Population trend: a curve such as average crying changing over early weeks.
- Caregiving practice band: an everyday recommendation relevant across a season.
Week numbers are navigation. They do not turn a month-level or population-level source into a week-precise prediction.
When corrected age applies
We estimate gestational age as 40 weeks minus the days between birthday and expected due date. Correction is offered only when that estimate is before 37 completed weeks, which means at least 22 days early. It applies only to developmental notes supported by corrected-age guidance. It stops on the child’s second birthday. Actual age remains the calendar marker.
The expected due date is the clinical estimate of when pregnancy reaches 40 weeks. To catch likely year or date-entry mistakes, this calculator asks parents to recheck records when the dates are more than 20 weeks apart. It does not reinterpret the clinical record. See the NHS explanation of expected due dates.
What we deliberately exclude
- Scores, pass or fail states and comparisons between children.
- Calendars that assign every baby the same fussy phase or named “leap.”
- Fixed sleep-regression weeks.
- Universal growth-spurt weeks inferred from anecdotes.
When a topic deserves its own URL
Timeline points do not generate pages automatically. A supporting page needs a written editorial plan, enough distinct evidence to answer a real parent question, multiple relevant claims, and content that is useful without entering baby details. Similar questions are grouped together instead of being split across thin week pages.
Our initial internal threshold for a week or age-range page is at least four evidence units, two unique claims, two timeline layers, and two independent source organisations (or one definitive standard with a reviewer exception). Topic guides require a broader evidence base across several age windows.
Global first, local when needed
WHO and international research establish the global base. National sources add practical public guidance. NHS and NICE advice is valued and marked as UK-specific when it describes a care pathway or recommendation that may differ elsewhere.
How privacy works
The public chronology is static HTML. A small local script calculates age, remembers layer choices and marks “now.” Name, birthday, due date and pronouns remain in local browser storage and never enter URLs, page metadata or network requests.
Correction and review
Sources record the date checked. Claims can be revised independently of presentation. The source ledger records what was checked and when. A named clinical and editorial review, together with a visible corrections route, is still required before this work is treated as final clinical guidance.