Every pregnant woman wants to know her due date. But a due date calculated from last menstrual period with a due date calculator often doesnt match the due date that is estimated by ultrasound (also known as a sonogram).

How common is it for due date to be wrong?

In fact, only 6% of women deliver on their due date, Cackovic said. I tell patients that really, your due date is a date in the middle of almost a month-long period of time that you could have your baby. The reality is that about 70% of women will have their baby within 10 days of their due date, he said.

Are due dates 100% accurate?

But data from the Perinatal Institute, a non-profit organisation, shows that an estimated date of delivery is rarely accurate - in fact, a baby is born on its predicted due date just 4% of the time.

How accurate are ultrasound due dates?

How accurate is the ultrasound examination? The earlier the ultrasound is done, the more accurate it is at estimating the babys due date. Ultrasounds performed during the first 12 weeks of pregnancy are generally within 3 - 5 days of accuracy. The most accurate time is between 8 and 11 weeks gestation.

When is my due date if my period is longer than 28 days?

How accurate is the due date? The pregnancy calculator gives you an approximate due date, which it works out your due date by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28 day cycle, it is adjusted for longer or shorter cycles).