The due date is an estimate. Only about 4% of babies are born precisely on their calculated due date. Most babies arrive within a window of 2 weeks before or 2 weeks after the calculated date.

Yes. Standard due date calculations assume a regular 28-day cycle. If your cycle is longer (e.g., 32 days), your ovulation happened later, and your actual due date will be adjusted forward by a few days.

Early first-trimester ultrasounds measure crown-rump length, which is the most reliable way to date a pregnancy. If there is a discrepancy of more than 7 days, your obstetrician will likely adjust your official due date based on the scan.