About the EDD and/or EDC issue, and a request for input from readers

EDD stands for Estimated Date of Delivery, while EDC stands for Estimated Date of Confinement (the time of going to hospital for the delivery, “the lying-in of a woman in childbed“).

Seasonality of Google Searches Bears Out These Thoughts And Plans

August and July, October and/or September are the months of the season of most births in the U.S. And Mums-To-Be are rather anxious about the timing of the pregnancy-to-birthing process, gestation.

Just see how, well ahead of the upcoming birth time, the interest in the search term “gestation” peaks every year in April, give or take a month. You can see it at https://www.google.com/trends/explore?date=2004-12-31%202017-01-18&geo=US&q=gestation (search terms: United States, 12/31/04 – 1/18/17, All categories, Web Search). I’ll expand on the seasonality aspect below, after I share some thoughts and plans.

The bioZhena thinking, in one brief sentence, is this: Aim to replace stochastic with deterministic, which is the purpose of our eukairosicTM diagnostic tools. Then the E in EDD and EDC will stand for EXPECTED.

‘Expected’ based on a measured data based computation, as opposed to a subjective recall based physician’s guess. Because, as I say in the very last sentence at the end of this article: Your approaching EDD and EDC are not normalized/relative like those in the statistical graph …

The medical position on the current status of obstetrics can be characterized by the following two papers.

1) Theory of obstetrics: an epidemiologic framework for justifying medically indicated early delivery

[BMC Pregnancy Childbirth. 2007 Mar 28;7:4. Joseph KS, Perinatal Epidemiology Research Unit, Department of Obstetrics & Gynaecology, Dalhousie University, Halifax, Nova Scotia, Canada]

QUOTE: Modern obstetrics is faced with a serious paradox. Obstetric practice is becoming increasingly interventionist … Whereas … mortality declines exponentially with increasing gestational duration, temporal increases in medically indicated labour induction and cesarean delivery have resulted in rising rates of preterm birth and declining rates of post-term birth. … [This] provides a theoretical justification for medically indicated early delivery and reconciles the contemporary divide between obstetric theory and obstetric practice. END QUOTE.

And 2) A re-look at the duration of human pregnancy

[Singapore Med J. 2006 Dec;47(12):1044-8. Bhat RA and Kushtagi P, Department of Obstetrics and Gynaecology, Kasturba Medical College, Manipal, India]

QUOTE: The duration of human pregnancy is arbitrarily taken as 280 days (40 weeks). Foetuses are considered to be at high risk once pregnancy goes beyond the expected date of confinement. … Conclusion: Mean gestational age at the onset of labour for women native to the area of study was 272 days (standard deviation 9 days). Pregnancies beyond a duration of 280 days showed significantly increased perinatal morbidity. It is suggested that there is a need for determining the length of gestation and to compile gestation-wise incidence of … neonatal morbidity indicators for different populations. END QUOTE.

Related medical publications are here.

I will rely on the birthing specialist, Janelle Durham, to verbalize for you the status quo in this aspect of the homo sapiens experience – below. First,

Gestation Period, Gestational Age and OvulonaTM

Per Encyclopedia of Childhood and Adolescence, article Gestation Period and Gestational Age ,

” a gestation period of thirty-eight weeks (266 days) is calculated for women who are pregnant by a procedure such as in vitro fertilization or artificial insemination that allows them to know their exact date of conception.”

The Ovulona device from bioZhena will provide to the woman user a very simple means to record the day of any intercourse as a part of her record of the menstrual cyclic profile. In every cycle, whether pregnancy is planned or not. This must become a part of the routine. The information will be electronically recorded along with the daily or almost-daily measurement data inherent in the use of the Ovulona.

With that menstrual cycling history data, this intercourse-timing information will be available for optional use by the woman’s physician(s). And in due course (contingent on funding) the cervical ring transformation of the Ovulona will remove the need for daily insertion…

Therefore, the routine use of the Ovulona (and of the internally worn HaloTM cervical ring) will provide for an equivalent of the above-referenced 38-week (266 days) calculation available to the women receiving IVF or artificial insemination. This alone should be an improvement on the current way of EDD/EDC assessment. In this context, an investigation should be undertaken into the question of whether any inference can be drawn from the woman’s menstrual cycle history prior to the conceptive (baby-making) intercourse.

Any comments on this would be welcome, even about anecdotal or subjective or tentative observations that may be available. However non-scientific, however tentative, however uncertain an individual answer or input from you may be…


Questions such as: What evidence is available in medical literature (or maybe in unpublished records?) about the outcomes of the IVF or artificial insemination pregnancies, i.e. about their documented gestation periods? Does the 38 weeks projection work? Always? If not always, can anything be correlated with any deviation?

Has anyone looked at whether there may be an effect of geography in terms of hot vs. cold climate on gestation periods of natives? And perhaps even at whether a gestation-period difference may arise in data at a well-selected locale between winter and summer deliveries (of course only natural, not “medically indicated early deliveries”)?

The complicating effect of first versus subsequent pregnancy has already been noted, of course… That evidence exists for gestational length variability with ethnicity (or race) has been noted, too:

“122,415 nulliparous women with singleton live fetuses at the time of spontaneous labour, giving birth in the former North West Thames Health Region, London, UK. Results: The median gestational age at delivery was 39 weeks in Blacks and Asians and 40 weeks in white Europeans.” [International Journal of Epidemiology 2004, Volume 33, Number 1, pp. 107-113 ].

I am happy to observe that this outcome is not counter-intuitive (because women with ancestors in hot climates seem to tend to shorter gestational age at delivery than those who can be presumed to originate from colder climate conditions).

Conceivably, such a preliminary info, which I am after here, is not forthcoming — and we shall have to try and gather even these preliminary data in a systematic manner when the time comes, but no question asked, nothing learned… Public or private input would be appreciated. (I wrote this request here in 2008.)

Although focused on the very serious complication in pregnancy, A Balancing Act: Ideal Delivery Timing & Chronic Hypertension by Eva Martin, MD is an example of the kind of information that we will need when setting out to start the adaptation of our technology to the challenge of assessing and managing EDD/EDC. Retweeting her piece, I tweeted in April 2017: This is why when the monitoring will better assess EDD/EDC >abandon old Naegele rule.

Dr. Martin has a few videos online on the subject of due dates, and here is one of them (~2 minutes): How to Calculate Your Due Date After A.R.T. –  https://www.youtube.com/watch?v=G4OCSwxTEIg  (in a nutshell: Fertilization + 266 days [38 weeks] as we already noted above, with reference to the Encyclopedia of Childhood and Adolescence).

There in any case does seem to be some, perhaps fairly good, basis for this attempt at a preparation for an introduction of a tool for definitive assessment of EDD and EDC.

Due Dates Paper by Ms. Durham

According to the due dates paper by Janelle Durham, written for Certification with Birth Education in January, 2002 , QUOTE: “some women are aware of when they ovulate, either based on formal methods and record-keeping such as daily temperature checks, or on physical symptoms such as mild pain upon ovulation, or observation of changes in vaginal mucus. Many women know the dates when conception was possible, because they know the dates when they had intercourse during their most recent menstrual cycle.

Due dates can be calculated based on these dates, but many physicians prefer to calculate it from date of last menstrual period. They may only calculate from conception date if conception was medically managed and supervised through techniques such as artificial insemination.

Based on date of last normal menstrual period.

Due dates are typically calculated based upon the date the last menstrual period began, according to the mother’s report. Naegele’s rule assumes that ovulation occurred 14 days after LMP, which is only the case for women with 28 day cycles. Some caregivers will ask their patients for a history of menstrual cycles so that they can adjust this number, as appropriate, for cycles of different lengths or irregular cycles.

It’s also important to consider: recent use of oral contraceptives, and their possible effect on ovulation date; inaccurate memory about when the last period occurred, the possibility of interpreting post-conception ‘spotting’ as a light period, and unrecognized pregnancy losses. These issues all complicate due date prediction, and it’s estimated that nearly 25% of infants who would be classified as preterm birth on the basis of the last normal menstrual period are not preterm. (Cited in Health Canada)” END QUOTE.

At this point, let me translate the one brief sentence I wrote at the top into a less specialist language. Ms. Durham shows a statistical distribution of gestation periods applicable to any woman, and that is the approach I labeled stochastic, because of its statistical nature. I admit, the word is harking back to the days of my postgrad phys chem endeavors, which were mostly endeavours at the time. 🙂 We could also say, probabilistic – two syllables longer, though!

Gestational Age at Birth vs. Weeks since LMP


Janelle Durham, for Certification with Birth Education NW. January, 2002.


Our Goal Your Comments

With our eurokairosicTM diagnostic tools, we generally aim to determine the right time, and in the case at hand we propose to provide for a much less fuzzy assessment of the EDD and EDC. After all, precedent exists in the A.R.T. arena, and prerequisites, too, to some extent at least.

In a nutshell: Let’s replace the LMP/Naegele-based approach with a hard data-based technique, applied to each and by each Mom individually.

Again, your comments on and/or answers to the questions above would be useful. Public or private input would be appreciated. [Private to: vaclav@biozhena.com please.]

In any case, for more on this topic see a related post published on December 8, 2010: Saint Nicholas Day, his legend, and our modern day’s prematurity, EDD calculation, gestational age, problem with LMP. We show there data from a study of more than 24.5 thousand pregnancies demonstrating that “most (71.5%) inductions done post-term (> 294 days) according to LMP dates were not post-term if ultrasound scan dates alone are used to calculate the gestational age.”


It is perfectly reasonable a vision that, in future, an expectant mother’s EDD and/or EDC will be assessed based on her folliculogenesis in vivo (FIV™) data which will include the electronic record of every sexual intercourse. The EDD/EDC will be computed automatically and provided by her own Ovulona Smart Sensor™.

So that, for example, a woman in and native to (or perhaps with ancestry from) a hot climate area might automatically obtain her EDD of 39 weeks when she electronically registers her day of intercourse on her Ovulona. Versus 40 weeks for a white European, consistent with the knowledge base noted above and assuming its validation.

No more uncertainties as in the LMP-based estimation. The bell-shape curve of distribution (such as the Janelle Durham graph above) will be replaced by personalized specifics.

Seasonality of EDC Searches on Google

On June 1, 2015 (at about the time of the year when, statistically, most American expectant mothers are about the last trimester away from their Estimated Date of Delivery and of Confinement) I add the following illustration. It appears to suggest why in May and June each year for the last 6 years there is always a noticeable increase in the viewing statistic of this blog post that you are reading. The interest is up.

Seasonality of Search Google Trends for search term “EDC” 2009 - 2015

See the image better as Single slide – Google Trends for EDC Search 2009 – 2015 e

Check the trend for yourself by moving from the screen shot image to the actual graph online via the link http://v.gd/c2MOyR i.e. http://www.google.com/trends/explore#cat=0-45&q=edc&geo=US&date=1%2F2009%2078m&cmpt=q&tz= . Once online, the Google graph shows (with cursor put on data for different months) the counts of US searches for EDC in the different months. You can change the range of the time period via the Time button, and the country of interest via the Country button. The numbers represent search interest relative to the highest point on the chart. At the time of writing this, it was the number of searches in June 2014 (assigned the maximal relative value of 100).

Move the cursor along the graph to see the values for other months within the examined period. You’ll see the EDC value of 100 in June 2014; in June 2013 the US peak was at 72 counts. The worldwide trend is much like the US trend because the statistics are driven by the overwhelming majority of American searches. E.g. the May 2015 count worldwide is only higher by 7 more searches than the US value of 48; in June 2014 the worldwide count was the same 100 as the US while in June 2013 the worldwide count was 20 counts higher than the US count of 65.

That’s as of June 3, 2015. Might this change later? Well, click http://www.google.com/trends/explore#cat=0-45&q=edc&geo=US&date=1%2F2009%2082m&cmpt=q&tz=Etc%2FGMT%2B6 and see the graph as of September 12, 2015, which does show the June 2015 peak indubitably.

The worldwide count can be obtained via the Country button on the Explore bar in Google Trends (USA was selected here). The data are normalized, relative numbers – you can read up on it… It’s a Google algorithm.

And here now is a January 6, 2017 update of the Google Trends EDC results, showing that the June peak (in search activity for EDC) continues to be there; in June 2016 it stood at 88 while in June 2015 it was 89, as found by placing the cursor on the peak in the online graph (only one data point can be screen-printed as in the image here) – the URL is below the image:




Dear Reader,

Your approaching EDD and EDC – if indeed their coming up is the reason why you are reading this – are not normalized or relative values like those in the statistical graph

— and good luck, all the best from bioZhena!



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2 Responses to “About the EDD and/or EDC issue, and a request for input from readers”

  1. hakexp Says:

    It makes me uncomfortable when someone just reaches out and pats my belly..Then I have some people touch my belly and it seems totally natural. So for me It depends on who it is. I’ve had 1 person ask if she may touch my belly in 34 weeks of pregnancy and it made my day that she would have enough respect to ask…

  2. Saint Nicholas Day, a legend about his saving three sisters, and our modern day’s prematurity « bioZhena’s Weblog Says:

    […] but prematurity is “before 37 weeks”? (A week here, a week there…) Read also the earlier post https://biozhena.wordpress.com/2008/01/11/about-the-edd-andor-edc-issue-and-a-request-for-input-from-… . Tomáš Císarovský – […]

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