Many online resources state that it's very unlikely for a pregnancy to result in a delivery exactly on the estimated due date. I've seen the number of about 5%, but can't find it nor am much interested in this information specifically.
There is also a popular opinion saying that the first pregnancy natural labor usually happens after a due date rather than on or before it.
As you can tell, I am a bit skeptical about it. Could anyone point me to an official source that has the information on the distribution of terms of the natural labors in the first pregnancies?
Here's a link to a site that says:
Babies don't always arrive when they're supposed to, and mothers often say firstborns tend to be late, although this conclusion is typically based on anecdotal reports
He [Allen Downey] found that first babies were, indeed, slightly more likely to be born late, at 41 weeks or later, compared with other babies (second-borns, third-borns, etc.)
I do not know if this question is location related. But for the sake of specificity you can assume I'm asking about the United States.