We no Longer Recommend "Due Dates" But Would Prefer "Due Weeks"

 If you have plans to fly in to see your mom on a particular day, she will ask you what time you are arriving. When your obstetrician has assigned you a day to deliver, it wouldn't occur to you to ask "what time," you understand the birthing prediction process is not at all that specific. In fact, there has been a concept of "term" (completed) pregnancy that used to be defined as over 37 weeks, as long as it was under 42 weeks. Obstetricians used to consider "term pregnancy" or "ready to be born pregnancy" between 37 weeks of pregnancy and essentially we have thought of your "birth month" and pretty much never thought of a "specific due date" in the way so many women do. And to formalize this concept, and realize that there is a "healthier time to deliver" than too early or too late. So on December 17th 2012 the NICHHD convened a meeting of important providers of women's health such as ACOG, AAP, WHO, March of Dimes to discuss how we were really going to define "term" Most information they were considering reflects risks of dying (mortality)and not risks of other problems (morbidity), so I look for further refinement of these criteria. Pregnancies between 37 weeks and 38 weeks and 6 days do not have as healthy babies as pregnancies between 39 and 41 weeks and 6 days. The experts don't want the docs to think of a specific due date, they came up with the terms "early term, full term (the 39 to 41 weeks and 6 days), late term and post term. The next issue is how you even get to that date: your period or a sono, but that's a different post topic! But for now, I suggest you tell the family, the "due weeks"...and not a due date...it's the healthy way to think of dating a pregnancy!


  1. Due dates using naegle's rule are not accurate indeed. I don't know if you heard of mittendorf-williams rule but it's supposed to be more accurate. However, I agree with you that we really should use the term due week. Mittendorf-williams method uses your age, height weight and other statistics to find a more accurate "due date". You can try it online at http://www.yourduedate.com/?advanced

  2. It's an intriguing statistical exercise to use maternal factors to predict the due date, but it's really controlled by the baby. We know that the baby grows for approximately 280 menstrual days minus the 2 weeks of ovulation, so 266 days. The trick is predicting when it all started. For those with fertility treatments such as IVF we know when fertilization occurs, with the rest of the moms it's a bit of mystery for the obstetrician to solve!

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  4. Are you pregnant? here is your pregnancy calculator _calculate your pregnancy due date online and easily....enter the first day of your last menstrual period:
    Use our pregnancy calculator and Get information when was your conception date, when your NT ultrasound should be, your anatomy scan should be and your due date will be…


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