For preemie parents

Your baby was born early. Your calendar should know that.

Development runs on the due-date clock, not the birth-date clock. Pediatricians call it adjusted age, and they use it until around age 2. Every tool and every guide on this page is built on that calendar — the one that is fair to babies born early.

See where your baby really is

Enter the birth date and the due date, and the forecast maps the whole first year on your baby's adjusted age. Free, no signup, stays on your device.

Open the forecast with adjusted age

Start here

Adjusted age, explained

What it is, how to calculate it in ten seconds, and why doctors use it until around age 2.

Milestones by adjusted age

The AAP milestone list on the calendar that is fair to your baby, month by month.

Home from the NICU

The first weeks home: safe sleep on the due-date clock, visitors and germs, follow-ups, and looking after yourselves.

When do preemies catch up?

Where the famous "by age 2" line comes from, and why babies born very early may need longer.

The short answers first

Should I count from the birth date or the due date?

For development — rolling, smiling, sitting, fussy phases — count from the due date. For vaccines and most medical schedules, doctors usually use the birth date. When in doubt, ask your pediatrician which clock applies.

Is my baby behind?

Measured on adjusted age, most preemies are exactly where they should be. Comparing a baby born 8 weeks early against full-term babies of the same birth date is comparing two different calendars. If milestones are missing on adjusted age, that is the moment to talk to your doctor — and your own concern is always reason enough to call.

Do fussy phases follow adjusted age too?

Yes. Even the original 1992 research counted from the due date, not the birth date. That is why our forecast asks for both dates and does the adjusting for you.

Written in plain language, checked against CDC, AAP and NHS guidance, with every source cited on each page. Not medical advice: for anything that worries you, your care team knows your baby best.

Peanutbean provides general information for educational purposes only. It is not medical advice. Every baby develops at their own pace. Always talk to your pediatrician about your child's health.