Our calculator is based on an analysis of public birth certificate data from the CDC's Division of Vital Statistics on live births between 2006 and 2010.
Very few babies actually arrive on their due date, and many arrive more than a week away from their due date. Of all the babies born in the U.S., less than half arrived within a week of the due date.
When you complete our survey, we use your responses to identify the birth records of women with exactly the same characteristics. We then show you information on when those women gave birth and the average weight of their babies.
Of course, a prediction is just a best guess based on the available data. There is no way of knowing exactly when your baby will come, as there are many factors at play. The predictions are right "on average," but of course not everyone is average! That’s why instead of giving you a single due date, we provide information on the chance that your baby will come each day for the rest of your pregnancy.
Check back as your pregnancy progresses, as the results are updated as you progress from each day to the next.
Any questions? Feel free to email us at [email protected] or connect with us on Twitter @whentoexpect.