Gentle arithmetic
When will little one arrive?
A due date is a best guess, not a deadline. Babies come when they come — usually sometime in a two-week window around this date.
How this works
From the first day of your last period, we add 280 days — that's Naegele's rule, the standard method most providers use. Conception-date gets 266 days (you're already two weeks in). IVF transfer subtracts the embryo's age: a day-5 transfer adds 261, a day-3 transfer adds 263.
These estimates drift a little if your cycles aren't exactly 28 days. An early ultrasound's measurement is often more accurate after week 8.