How we build the list: where each number comes from

The three bases

1. The catalog. Baby items, from bodysuits to the bathtub, each with how many to have in each size, by approach (essential, balanced or complete) and by the weather of the month. Every number has a source or is labeled as a Cotokim proposal, with the reasoning. The sources are pages from health agencies, laws, standards and manufacturers, read and saved with the date we read them.
2. Your city's weather. The typical temperature of each month in US cities, from the climate normals that NOAA measures at its weather stations ¹.
3. How your baby grows. The World Health Organization median length and weight curves tell us in which months your baby is likely to wear each size of clothes and diapers ^{2 3}.

How the weather goes into the list

For each month your baby wears a size, we look at the typical average temperature of your city. Below a certain monthly average, the month counts as cold; above another, as hot. Those cutoffs are our proposal: we found no health source that sorts months by the outdoor temperature to dress a baby. Temperatures show in °F, with °C next to them when the math is ours.

A city gets its own numbers only when a NOAA weather station with all twelve monthly normals is within 25 km (about 15 miles) of it and within 150 m (about 490 feet) of its elevation ¹. NOAA itself warns that normals fit less well the farther you are from the station, and that is why we keep this distance short.

How age turns into size

The label on baby clothes says an age, but babies fit by length and weight. We use the World Health Organization median curves to estimate when a typical baby moves from one size to the next ^{3 2}. Every brand fits differently, so when in doubt, compare your baby's length with the brand's chart.

Numbers that match

The number you read in a page's text comes from the same base the tool uses, when the page is built. If a quantity changes in the catalog, the tool and every text that mentions it change together. No number from our math is typed by hand.

Who checks the health content

Today, what Cotokim says about health is checked against the sources of each page by the Cotokim team, with the AI tools described below. No health professional has reviewed the site yet. To decide, we always follow the same rules:

• Official US sources first: the CDC, the NIH Safe to Sleep campaign, the CPSC and NHTSA ⁴. When we mention the American Academy of Pediatrics, we cite it by name, with a link, in our own words.
• When official sources disagree, the page shows both, says which one we follow and why, and asks you to follow the team caring for your baby.
• For safe sleep and injury prevention, we always follow the strictest official guidance.
• A quantity with no health source is a Cotokim proposal and is labeled as one, unless a source contradicts it.
• A warning sign always ends with what to do: call your baby's care team and, when the source says so, go to the emergency room or call emergency services.

How we use AI

Cotokim's pages and lists are written with AI tools (large language models) that we direct, working from the official sources and from our data. The AI does not type the numbers into the text: every quantity comes from the catalog and the weather data, through the same math the tool uses, and in the catalog each number has a source or is labeled as a Cotokim proposal. Each health sentence is checked against the saved excerpt of its source, with the date it was read, in a separate review, also done with AI tools, that did not write the page. No health professional has reviewed the site yet, and the advice of the people caring for you and your baby comes first.

What Cotokim doesn't do

• It doesn't sell products: it is not a store and has no inventory.
• It doesn't use your due date or any pregnancy data for ads, and it doesn't sell data.
• It doesn't hide where a number comes from: each page shows its sources, with the date they were read.