How Accurate Are Due Dates? They Aren't Exact

Parenthood is anything but predictable, which is why it's nice to know that your ticket to the journey of motherhood has an arrival date — your due date. But how accurate are due dates? Does it actually mean anything if you go past yours? Are they set in stone or are they flexible dates for your womb mate's evacuation?

Everyone loves knowing their due date, but their accuracy isn't always 100 percent. According to Parents, when you head to your doctor for that first "I'm pregnant" visit, they will calculate your due date by taking the first day of your last period and adding 280 days (the number of days in 40 weeks of pregnancy) to it. That's the roundabout due date they give you, but as Parents noted, unless you have a perfect 28 day cycle, that's not entirely accurate, which is why you're usually given an early scan in those first few weeks of pregnancy.

BBC News noted that this is the same practice in the UK, and that if your ultrasound (which measures the fetus and can determine the approximate age of your pregnancy based on the baby's size) differs by a week or more, your due date can change as the scan is considered to be a more accurate measurement than the original counting method.

The American College of Obstetricians and Gynecologists agreed. In 2014, they noted that an ultrasound measurement in the first trimester is the most accurate way to find out the gestational age of a pregnancy and a woman's due date. But that doesn't mean the due dates are set in stone. According to Fit Pregnancy, your due date is simply an estimate. In fact, only about five percent of babies are spontaneously born on their due date, not counting the ones that are induced.

Baby Center noted that you're just as likely to go into labor two weeks before or after your due date and that the date isn't 100 percent accurate. It can be frustrating to wait it out, but look at your due date as a light at the end of the tunnel, even if you pass by it while you're still pregnant.

March of Dimes actually suggested that this is one of the reasons why inductions can be so dangerous — your due date may not be exactly right. So be patient and wait it out, mama. No matter what, your baby will be worth it.