18 thoughts on “Your Due Date Is Wrong–So When Is Labor Most Likely?”

  1. I love this topic. Fortunately my OB was really relaxed about the due date, but I always feel bad for women who start to feel a lot of pressure to be induced when there isn’t an obvious reason to (like an ultrasound indicating there is potential for fetal distress/macrosomia/problems with amniotic fluid). I had two due dates, May 4th, 2013 based on an ultrasound at 6 weeks and May 8th based on LMP. I had the sweep on May 9th (after having an ultrasound where everything looked healthy– but the baby was definitely estimated to be over 9 lbs) and went into labor right away, and delivered May 11th (just past midnight); so about a week past my U/S due date and a few days past my LMP one. Oh, and this reminded me of this site: http://spacefem.com/pregnant/charts/duedate0.php

    1. Nice that your doctor was relaxed and respectful of your wishes!

      Did you baby end up over 9 lbs at birth? It sounds like weight estimation using ultrasounds can be pretty inaccurate.

      1. They estimated 9 lbs 3 oz and he was 9 lbs 7 oz two days later when he was born. I think the accuracy probably depends a lot on the experience of the technician and quality of the machine.

  2. My due dates were calculated by last menstrual period; my firstborn was 10 days ‘early’ and my seconnd was nearly two weekes ‘late’.

  3. The key here is that the above statement is true if labor is imminent. If it is say, a week away, then having an induction lowers the risk of a c-section.

    After reading through all the research on this, the one take home message seems to be that after 41 weeks, having an induction is not going to raise your chances of a c-section; it will almost certainly lower it.

  4. Could you do (or have you already done) a review of the data on inducing labor in “elderly women” to prevent stillbirths? I am 41 years old and pregnant with my 4th child. I know the apparent standard practice is to induce at 39 weeks based on data from small study where is it suggested that stillbirth risk is that of younger women at that time. I’m vehemently opposed to the idea. I have had one experience with oxytocin after 2 completely unmedicated births and it was human torture. I am a physician in a non-OB field. In my perfunctory review of some data, I think there is excessive medicalization and intervention in birthing. Thank you.

    1. Great idea–I am going to add it to my queue. I did not know that this was standard practice. Would you send me any info you have about this being standard and the alleged rationale?

  5. Another question I’d love to know… How do these stats change based on your previous children. For example: my son (healthy, normal pregnancy) came three weeks before his “due date.” So early no matter how you look at it really. What are my chances of having another early baby – are they increased at all? (Assuming another healthy pregancy, of course).

  6. Hi, just want to add to this terrific post that in both France and Germany (where I’ve had prenatal appointments) the due date is calculated to be a week and two weeks later, respectively, than in the US (where I’m based). I wonder whether in Asian / African countries the standard calculation is also different, to reflect the earlier delivery cited in the study you linked to above? (Also, since that study was based in London, sampling women of African or Asian *descent*, I wonder whether there’s a difference between African / Asian women actually in African / Asian countries and those in Caucasian-majority countries?) Thanks again for your intriguing discoveries and discussions!

  7. I’m the exception to the rule not to count on the due date being the delivery date. My two vaginal births occurred on their due dates. with #1, my water broke the day before my due date and I was induced the next morning and delivered in the evening. With #3, I went into natural labor at home in the morning at about 9 am, arrived at the hospital at 6cm at about 1 p.m and delivered at the hospital at 2:46 (weirdly enough on the operating table as they were preparing to put me out for an emergency c-section due to fetal distress when I said “the baby is coming” and then checked and then told me to push, it turned out he had a true knot in his umbilical cord and the cord was wrapped twice around his neck). I know with my first pregnancy that I had a standard 25 day cycle and ovulated on day ten, with a positive pregnancy test 10 days later, so if the doctor had gone by those dates, my son would have been late under Naegele’s rule. With #3 I ovulated around day 13, so had a more typical cycle length.

  8. I had my first baby ten days late, and he weighed 6 -10. My second was 26 days late (!) and weighed 7 – 4. The third was a csection around her due date, and she weighed 6 – 3 and they said she looked three or four weeks early. Go figure. My first grandchild is due tomorrow (son of the son who was 26 days late), but who knows!

  9. What a great article. I needed this ammunition in order to sound informed as my doctor wants to induce me at 41 weeks. I’m considering it since there are risks such as meconium etc. However I’d rather base it on evidence and if my fluid levels and stress tests are normal I see no reason to wait until 42 weeks. My mom had both my sister and I “late” so there is that genetic factor.

    My blood pressure has been rising a bit albeit still normal, so I just have to control that by exercising daily and a good diet.

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