When are they coming?
Naegele's rule (1812, still surprisingly accurate) plus a real picture of where you are right now — week, trimester, and what's happening next.
Only about 4% of babies are actually born on their predicted due date. About 80% arrive within two weeks of it, which is what "due date" really means — the middle of a window, not a deadline.
We use Naegele's rule (last menstrual period + 280 days), adjusted for cycle length when you tell us yours. First-trimester ultrasound dating is more accurate than LMP, so if you have an ultrasound date, we'll use that instead.
What we don't do: pretend the date is medical advice, factor in twins or IVF without your input, or guess at cycle length. Source: ACOG Committee Opinion on Estimating Due Date.
Every week of pregnancy mapped to your real calendar dates — hung on a cream wall, ready for the nursery.
Naegele's rule is the obstetric standard: count 280 days (40 weeks) forward from the first day of the last menstrual period. Adjusting by ±1 day per day of cycle-length deviation from 28 keeps it accurate for irregular cycles.
When you give us a known due date or conception date instead, we run the same math in reverse so the rest of the calendar (LMP, current week, full-term window) lines up.
- Only ~5% of births land exactly on the due date; ±2 weeks is normal.
- Naegele assumes a 28-day cycle and ovulation on day 14 — early ultrasound dating is more accurate when those don't hold.
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